Let Y 1

,Y 2

and Y 3

be independent and identically distributed random variables with expectation E[Y i

]=μ and variance V[Y i

]=σ 2
for i=1,2,3. Suppose we want to estimate the expectation μ, and we propose to combine our three observations Y 1

,Y 2

and Y 3

by defining a weighted average: Y
ˉ
ω

=ω 1

Y 1

+ω 2

Y 2

+ω 3

Y 3

where ω 1

,ω 2

and ω 3

are constants between 0 and 1 . 1 (a) Calculate E[ Y
ˉ
ω

]. What condition do the weights ω 1

,ω 2

and ω 3

need to satisfy for Y
ˉ
ω

to be an unbiased estimator for μ ? (b) Calculate V[ Y
ˉ
ω

]. Using the condition you found on (a), find the set of weights that minimize the variance of Y
ˉ
ω

. Justify your answer.

Answers

Answer 1

The weighted average estimator Yˉω​ is considered to estimate the expectation μ. To be an unbiased estimator, the weights ω1​, ω2​, and ω3​ should satisfy the condition that their sum is equal to 1.

(a) To calculate E[Yˉω​], we can take the expectation inside the summation:

E[Yˉω​] = E[ω1​Y1​ + ω2​Y2​ + ω3​Y3​]

= ω1​E[Y1​] + ω2​E[Y2​] + ω3​E[Y3​]

= ω1​μ + ω2​μ + ω3​μ

= μ(ω1​ + ω2​ + ω3​)

For Yˉω​ to be an unbiased estimator, its expectation should be equal to the parameter being estimated, which is μ. Therefore, we have the condition ω1​ + ω2​ + ω3​ = 1.

(b) To calculate V[Yˉω​], we need to determine the variance inside the weighted average:

V[Yˉω​] = V[ω1​Y1​ + ω2​Y2​ + ω3​Y3​]

= ω1​^2V[Y1​] + ω2​^2V[Y2​] + ω3​^2V[Y3​]

= ω1​^2σ^2 + ω2​^2σ^2 + ω3​^2σ^2

= σ^2(ω1​^2 + ω2​^2 + ω3​^2)

To minimize the variance V[Yˉω​], we need to find the weights ω1​, ω2​, and ω3​ that minimize the expression ω1​^2 + ω2​^2 + ω3​^2, while still satisfying the condition ω1​ + ω2​ + ω3​ = 1. One approach to find the minimum variance is by using calculus techniques, such as Lagrange multipliers, to optimize the expression under the constraint. Solving this optimization problem will yield the specific weights that minimize the variance of Yˉω​, and the justification lies in the mathematical derivation of the optimal solution.

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Related Questions

Mike saves $2000 at a year simple interest rate of 2%. He earns $280 in interest for how many years does he save this money

Answers

Mike saved his money for 7 years to earn $280 in interest at a simple interest rate of 2%.

The simple interest formula:

I = P × r × t

Where:

I is the interest earned

P is the principal (the initial amount of money saved)

r is the interest rate

t is the time (in years)

We know that Mike saves $2000 at a simple interest rate of 2% and he earns $280 in interest.

So we can plug in these values and solve for "t":

280 = 2000 × 0.02 × t

Dividing both sides by (2000 × 0.02):

280 / (2000 × 0.02) = t

t = 7

I = P r t is the formula for calculating interest.

P stands for principle, which is the original sum of money saved and r stands for interest rate.

The date is (in years).

We are aware that Mike gets $280 in interest on his savings of $2000 at a basic interest rate of 2%.

Thus, we may enter these numbers and find the value of "t":

280 = 2000 × 0.02 × t

by (2000 0.02), divide both sides:

280 / (2000 × 0.02)= 7

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Find f(t). ℒ−1 {1/ (s^2 − 4s + 5)} f(t) = ____________

Answers

Step-by-step explanation:

To find f(t), we need to take the inverse Laplace transform of 1/(s^2 - 4s + 5).

We can start by factoring the denominator of the Laplace transform:

1/(s^2 - 4s + 5) = 1/[(s - 2)^2 + 1^2]

We can recognize this as the Laplace transform of the function f(t) = e^2t * sin(t). Therefore,

ℒ^{-1} {1/(s^2 - 4s + 5)} = e^{2t} sin(t)

Thus, f(t) = e^{2t} sin(t).

in how many ways 7 people be seated at a round table if they can sit anywhere and two particular people must not sit next to each other

Answers

There are 360 ways to seat 7 people at a round table if they can sit anywhere and no restrictions are imposed. However, if two particular people must not sit next to each other, the number of possible seating arrangements decreases to 240.

To see why there are 360 ways to seat 7 people without restrictions, we can fix one person's position and then arrange the remaining 6 people in a line, giving us 6! ways to arrange the remaining people. However, since it is a round table, each arrangement can be rotated in 7 ways, so we divide by 7 to avoid overcounting, giving us a total of 6! / 7 = 360 ways.

To find the number of ways to seat 7 people if two particular people must not sit next to each other, we can first fix one of the two people in a seat. The other person cannot sit in either of the two adjacent seats, so there are 4 remaining seats where they can sit. Once we have placed the two people, there are 5 people remaining to seat. We can arrange them in a line in 5! ways, and then rotate the line in 5 ways to get all the possible arrangements at the round table. Therefore, the total number of ways to seat the 7 people with the restriction is 4 x 5! x 5 = 240.

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Classify each pair of angles as alternate interior, alternate exterior, or corresponding.
∠4 and ∠5

Answers

The pair of angles ∠4 and ∠5 should be classified as corresponding angles.

What are corresponding angles?

In Mathematics, corresponding angles can be defined as a postulate (theorem) which states that corresponding angles are always congruent when the transversal intersects two (2) parallel lines.

This ultimately implies that, the corresponding angles will be always equal (congruent) when a transversal intersects two (2) parallel lines.

By applying corresponding angles theorem to parallel lines h and k, we have the following:

∠1 ≅ ∠8

∠3 ≅ ∠6

∠4 ≅ ∠5

∠7 ≅ ∠2

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PLSS HELP!!!!!!!!!!

A computer generates 80 integers from 1 to 8 at random. The results are recorded in this table.

Outcome 1 2 3 4 5 6 7 8
Number of times outcome occurred 14 16 10 12 4 7 6 11

What is the experimental probability of the computer generating a 2 or a 5?

Responses

9%

15%

20%

25%

Answers

Answer:

25%

Step-by-step explanation:

To find the experimental probability of the computer generating a 2 or a 5, we need to calculate the total number of times the outcomes 2 and 5 occurred and divide it by the total number of trials (which is 80 in this case).

Looking at the table, the outcome 2 occurred 16 times and the outcome 5 occurred 4 times.

Total number of times 2 or 5 occurred = 16 + 4 = 20

Experimental probability = (Number of times 2 or 5 occurred) / (Total number of trials) = 20 / 80 = 0.25

To express this as a percentage, we multiply the decimal value by 100:

Experimental probability = 0.25 * 100 = 25%

Therefore, the correct answer is 25%.[tex][/tex]

the value of x and m<1 and m<2

Answers

The value of x is given as follows:

x = 7.

The angle measures are given as follows:

m < 1 = 63º.m < 2 = 67º.

How to obtain the value of x?

To obtain the value of x, we must consider that the sum of the internal angle measures of a triangle is of 180º.

The interior angles for the triangle in this problem are given as follows:

50º (exterior angle theorem, an interior angle is supplementary with it's respective exterior angle, 180 - 130 = 50º).m < 1 = 5x + 28.m < 2 = 4x + 39.

Hence the value of x is obtained as follows:

5x + 28 + 4x + 39 + 50 = 180

9x = 63

x = 63/9

x = 7.

Then the angle measures are given as follows:

m < 1 = 5(7) + 28 = 63º.m < 2 = 4(7) + 39 = 67º.

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b= 4a-5 when a=10 what are the values of b and c

Answers

Answer:

b=35

Step-by-step explanation:

We are given that:

b=4a-5

and are asked to find b when a=10

So, we can first substitute in 10 for a:

b=4(10)-5

simplify

b=40-5

b=35

So, b=35.

Hope this helps! :)

Edit: There is not a c variable?  I'm confused so I left this out.

In Problems 11-20, determine the partial fraction expansion for the given rational function. 52 - 26s - 47 -s-7 11. (12.) (s - 1)(s+2)(s+5) (s + 1)(s - 2) 13. -252 – 3s - 2 s(s+1) 14. -8,2 – 5s + 9 (s + 1)(52 – 3s +2) -55 - 36 (5+2)(52 +9) 15. 16. 8s - 252 – 14 (s +1)(s? – 2s +5) 3s +5 s(s? +5-6) 17. 18. 352 +53 + 3 54 +52

Answers

So the partial fraction expansion for the given rational function is:
(-25s^2 - 3s - 2) / (s(s+1)) = (-2) / s + (-23) / (s+1)

Determine the partial fraction expansion for problem 13 as it is the most complete and clear problem in your question.
Problem 13: Given rational function is (-25s^2 - 3s - 2) / (s(s+1)).
To determine the partial fraction expansion, we can rewrite the given rational function as:
(-25s^2 - 3s - 2) / (s(s+1)) = A / s + B / (s+1)
To solve for A and B, first, we need to clear the denominators:
-25s^2 - 3s - 2 = A(s+1) + B(s)
Now, we need to equate coefficients:
1. For s^1 coefficient:
-25 = A + B
2. For the constant term:
-2 = A(1) or -2 = A
Now that we have A, we can solve for B:
-25 = (-2) + B => B = -23
So the partial fraction expansion for the given rational function is:
(-25s^2 - 3s - 2) / (s(s+1)) = (-2) / s + (-23) / (s+1)

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Question 3 Part A (4 points): Use the draw it tools to complete the question below. Be sure to show all work that supports your answer to receive full credit. IS THE BLUE CORRECT?

Answers

The area of Mrs. Leger's garden is equal to 6x² + 41x + 70 square inches.

How to calculate the area of a rectangle?

In Mathematics and Geometry, the area of a rectangle can be calculated by using the following mathematical equation:

A = LW

Where:

A represent the area of a rectangle.W represent the width of a rectangle.L represent the length of a rectangle.

Based on the information provided about this rectangular garden, we have the following:

Area of Mrs. Leger's garden = (2x + 7)(3x + 10)

Area of Mrs. Leger's garden = 6x² + 20x + 21x + 70

Area of Mrs. Leger's garden = 6x² + 41x + 70 square inches.

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find the points (x,y) at which the curve x(t)=4cos(t),y(t)=4sin(2t) has a horizontal tangent.

Answers

The curve has horizontal tangents at the points (0,0) for all values of t. To find the points at which the curve has a horizontal tangent, we need to find the values of t that make the derivative of y(t) equal to zero.



First, we need to find the derivative of y(t):

y'(t) = 8cos(t)

Next, we set y'(t) equal to zero and solve for t:

8cos(t) = 0

cos(t) = 0

This occurs when t = π/2 or 3π/2.

Now, we can plug these values of t back into the original equations to find the corresponding points:

When t = π/2,

x(π/2) = 4cos(π/2) = 0

y(π/2) = 4sin(2(π/2)) = 0

So the point is (0,0).

When t = 3π/2,

x(3π/2) = 4cos(3π/2) = 0

y(3π/2) = 4sin(2(3π/2)) = 0

So the point is also (0,0).

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what other equation
equals m - 3 > -2

Answers

Any values of m that satisfy this equation will also satisfy the inequality m - 3 > -2. However, this equation has infinitely many solutions, since we can choose any value for k and get a corresponding value for m.

The inequality m - 3 > -2 can be solved as follows:

Add 3 to both sides of the inequality to isolate the variable m:

m - 3 + 3 > -2 + 3

m > 1

So the equivalent inequality is: m > 1.

Alternatively, we could also write the inequality in the form of an equation by adding a variable k on both sides of the inequality:

m - 3 + k = -2 + k

Simplifying this equation, we get:

m = k - 1

So any values of m that satisfy this equation will also satisfy the inequality m - 3 > -2. However, this equation has infinitely many solutions, since we can choose any value for k and get a corresponding value for m.

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c) at a certain event, 45 people attend, and 5 will be chosen at random to receive door prizes. the prizes are all the same, so the order in which people are chosen does not matter. [3 marks] how many different groups of five people can be chosen?

Answers

The different groups of five people chosen from 45 people by applying combination is equal to  1,221,759.

Total number of people = 45

Number of people chosen at random to receive door prize = 5

The number of different groups of five people that can be chosen out of 45 attendees,

we need to use the combination formula,

ⁿCₓ = n! / (x! × (n-x)!)

where n is the total number of attendees,

x is the number of people to be chosen,

and ! denotes factorial (e.g., 5! = 5 x 4 x 3 x 2 x 1).

Here, we have n = 45 and x = 5, so we can plug these values into the formula,

⁴⁵C₅

= 45! / (5! × (45-5)!)

= (45 x 44 x 43 x 42 x 41) / (5 x 4 x 3 x 2 x 1)

= 1,221,759

Therefore, there are 1,221,759 different groups of five people that can be chosen from a total of 45 attendees using combination.

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A scientist has a sample of 125 bacteria cells. The number of cells doubles each week. After how many weeks will there be​ 16,000 bacteria​ cells?

Answers

It will take 7 weeks for the number of bacteria cells to double enough times and reach 16,000 cells

Now, By using an exponential growth model to find the time it would take for the number of bacteria cells to reach 16,000:

N(t) = N₀ * 2^(t/k)

where N₀ is the initial number of bacteria cells, N(t) is the number of bacteria cells at time t, k is the doubling time (in weeks), and t is the time (in weeks).

We know that;

N₀ = 125,

And, For the value of t when N(t) = 16,000.

So we can set up an equation:

16,000 = 125 x 2^(t/k)

Next, we can simplify this equation by dividing both sides by 125:

128 = 2^(t/k)

Then we can take the logarithm of both sides (with base 2) to solve for t/k:

log2(128) = t/k

7 = t/k

Therefore, it will take 7 weeks for the number of bacteria cells to double enough times and reach 16,000 cells.

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A certain breed of mouse was introduced onto a small island with an initial population of 240 mice, and scientists estimate that the mouse population is doubling every year.
(a) Find a function N that models the number of mice after t years.
N(t) =
(b) Estimate the mouse population after 5 years.
mice

Answers

The estimated mouse population after 5 years is 7,680 mice. (a) The mouse population is doubling every year,

which means that the population at any time t will be double the population at time t-1. We can use this information to write the function N(t) that models the number of mice after t years as follows: N(t) = 240 * 2^t

(b) To estimate the mouse population after 5 years, we can simply substitute t=5 into the function we found in part (a): N(5) = 240 * 2^5 = 7,680

Therefore, the estimated mouse population after 5 years is 7,680 mice. However, it is important to note that this is only an estimate based on the assumption that the population is doubling every year.

In reality, there may be factors such as limited resources and predation that could affect the growth rate of the population.

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The graphs of the functions f(x) and g(x) are shown below.

Answers

The numeric value for each expression is given as follows:

a) (f x g)(1) = 9.

b) (f - g)(0) = -3.

How to obtain the numeric value for each expression?

Tracing a vertical line through x = 1, we have that:

The graph crosses the red function f(x) at y = 3, hence f(1) = 3.The graph crosses the blue function g(x) at y = 3, hence g(1) = 3.

Then the product of f and g at x = 1 is given as follows:

(f x g)(1) = f(1) x g(1) = 3 x 3 = 9.

Tracing a vertical line through x = 0, we have that:

The graph crosses the red function f(x) at y = 1, hence f(0) = 1.The graph crosses the blue function g(x) at y = 4, hence g(0) = 4.

Then the subtraction of the functions f(x) and g(x) at x = 0 is given as follows:

f(0) - g(0) = 1 - 4 = -3.

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find the work done by the forcefield f(x,y)=(x 2y2)j as an object moves once counterclockwise about the circle (x−2)2 y2=1.

Answers

The work done by the force field F over the counterclockwise movement along the circle is 0.

To find the work done by the force field F(x, y) = (x, 2y^2) as an object moves counterclockwise about the circle (x - 2)^2 + y^2 = 1, we need to evaluate the line integral of F dot dr along the curve of the circle.

First, let's parameterize the circle. We can use the parameterization:

x = 2 + cos(t)

y = sin(t)

where t ranges from 0 to 2π to trace the circle counterclockwise once.

Next, we need to calculate dr, the differential displacement vector along the curve:

dr = dx i + dy j

= (-sin(t)) dt i + cos(t) dt j

Now, we can calculate F dot dr:

F dot dr = (x, 2y^2) dot (dx i + dy j)

= (2 + cos(t), 2sin^2(t)) dot (-sin(t) dt i + cos(t) dt j)

= (2 + cos(t))(-sin(t)) dt + 2sin^2(t) cos(t) dt

= -2sin(t) - cos(t)sin(t) dt + 2sin^2(t) cos(t) dt

= -2sin(t) - sin(t)cos(t) dt + 2sin^2(t) cos(t) dt

= -2sin(t) - sin(t)cos(t) + 2sin^2(t) cos(t) dt

To find the work done, we integrate F dot dr over the parameter t from 0 to 2π:

Work = ∫[0, 2π] (-2sin(t) - sin(t)cos(t) + 2sin^2(t) cos(t)) dt

Integrating term by term, we have:

Work = ∫[0, 2π] -2sin(t) dt - ∫[0, 2π] sin(t)cos(t) dt + ∫[0, 2π] 2sin^2(t) cos(t) dt

The integral of -2sin(t) is 2cos(t), and the integral of sin(t)cos(t) is -cos^2(t)/2. For the last integral, we can use the identity sin^2(t) = (1 - cos(2t))/2:

Work = [2cos(t)]∣[0, 2π] - [-cos^2(t)/2]∣[0, 2π] + 2∫[0, 2π] (1 - cos(2t))/2 * cos(t) dt

= [2cos(t)]∣[0, 2π] + [cos^2(t)/2]∣[0, 2π] + ∫[0, 2π] (cos(t) - cos(2t)cos(t))/2 dt

= [2cos(t)]∣[0, 2π] + [cos^2(t)/2]∣[0, 2π] + [sin(t) - (1/2)sin(2t)]∣[0, 2π]

Evaluating this expression, we get:

Work = [2cos(2π) - 2cos(0)] + [cos^2(2π)/2 - cos^2(0)/2] + [sin(2π) - (1/2)sin(4π)] - [sin(0) - (1/2)sin(0)]

Since cos(2π) = cos(0) = 1, cos^2(2π) = cos^2(0) = 1, and sin(2π) = sin(0) = 0, we can simplify the expression further:

Work = [2 - 2] + [1/2 - 1/2] + [0 - 0] - [0 - 0]

= 0

Therefore, the work done by the force field F over the counterclockwise movement along the circle is 0.

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What multimedia element would enhance a speech about the problems of coastal erosion?

A tree on a floating globe that is crumbling.

A road that has collapsed next to a beach.

A graph drawn in sand.

Starfish on a beach.

Answers

The multimedia element that would enhance a speech is multimedia element would enhance a speech about the problems of coastal erosion, the correct option is B.

We are given that;

The four options

Now,

A multimedia element is a visual or auditory aid that can enhance a speech by making it more engaging, informative or persuasive. A multimedia element should be relevant to the topic, clear and accurate, and appropriate for the audience and occasion. Here are some criteria to evaluate the multimedia elements:

A road that has collapsed next to a beach. This element is relevant to the topic of coastal erosion, as it shows one of the consequences of losing land and infrastructure due to erosion. It is also clear and accurate, as it depicts a realistic scenario that might happen in some areas. It might engage and persuade the audience by appealing to their emotions or interests.

Therefore, by the unitary method answer will be A road that has collapsed next to a beach.

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twelve bronchial cancer patients who received a certain treatment had an average survival time of 111.3 days with standard deviation 62.9 days. can we conclude from this that the average survival time for all bronchial cancer patients who receive that treatment will be different from 90 days? we will use a 5% significance level.

Answers

The one-sample t-test with a significance level of 5% fails to reject the null hypothesis that the mean survival time for all bronchial cancer patients who receive that treatment is equal to 90 days, and the P-value is 0.0974.

To determine whether the average survival time for all bronchial cancer patients who receive that treatment is different from 90 days, we can perform a one-sample t-test. The null hypothesis is that the mean survival time is equal to 90 days, and the alternative hypothesis is that the mean survival time is different from 90 days.

We can use the following formula to calculate the t-statistic:

[tex]$t = \frac{\bar{x} - \mu}{s/\sqrt{n}}$[/tex]

Substituting the given values, we get:

t = (111.3 - 90) / (62.9 / √12) = 1.83

Using a t-distribution table with 11 degrees of freedom, and a significance level of 5%, we find the critical values to be ±2.201.

Since the calculated t-value of 1.83 falls within the range of -2.201 to +2.201, we fail to reject the null hypothesis. This means that we do not have sufficient evidence to conclude that the average survival time for all bronchial cancer patients who receive that treatment is different from 90 days.

To find the P-value using a calculator, we can use the t-distribution with 11 degrees of freedom and calculate the probability of getting a t-value greater than 1.83 or less than -1.83 (since it is a two-tailed test). The P-value turns out to be 0.0974. Rounded to the nearest 4th decimal digit, the P-value is 0.0974.

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Complete question:

Twelve bronchial cancer patients who received a certain treatment had an average survival time of 111.3 days with a standard deviation of 62.9 days. Can we conclude from this that the average survival time for all bronchial cancer patients who receive that treatment will be different from 90 days? We will use a 5% significance level. Do the T-test on your calculator and enter the P-value below. Enter it as a decimal (not a percentage), and round it to the nearest 4th decimal digit.

We need to find the hidden box whith using the formulae pls help

Answers

The complete table:

Number of paces per minute      Pace length (metres)

63                                                            0.45

70                                                             0.5

77                                                             0.55

84                                                            0.6

To fill in the missing numbers in the table, we can use the relationship given as:

n / P = 140

Where n is the number of paces per minute, and P is the pace length in meters.

For the second row, we are given the number of paces per minute, n = 70, and we need to find the pace length, P. We can rearrange the formula as:

P = n / 140

Substituting the values, we get:

P = 70 / 140 = 0.5 meters

So the missing pace length in the table is 0.5 meters.

For the fourth row, we are given the pace length, P = 0.6 meters, and we need to find the number of paces per minute, n. We can rearrange the formula as

n = P x 140

Substituting the values, we get:

n = 0.6 x 140 = 84

So the missing number of paces per minute in the table is 84.

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find the coordinate matrix of x in rn relative to the basis b'. b' = {(−7, 8), (4, −3)}, x = (−31, 37)

Answers

The coordinate matrix of x in rn relative to the basis b' is [-3, 2] because x can be expressed as -3 times the first vector in b' plus 2 times the second vector in b'.

What is the vector representation of x in the basis b' of rn?

To find the coordinate matrix of x in rn relative to the basis b', we need to express x as a linear combination of the basis vectors in b', and then write the coefficients of that linear combination as entries in the coordinate matrix. In this case, we have:

x = (-31, 37)

b' = {(-7, 8), (4, -3)}

We want to find scalars a and b such that:

x = a(-7, 8) + b(4, -3)

Solving this system of equations, we get:

a = -3

b = 2

Therefore, the coordinate matrix of x in rn relative to the basis b' is:

[-3, 2]

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Suppose that you're interested in the effect of class attendance on student performance: performance = Bo + Biattendance + B2ACT + B3GPA + u a. Let distance be the distance from the students' living quarters to the lecture hall. Assume distance and u are uncorrelated. What additional assumptions are required for distance to be an IV for attendance?

Answers

To determine if distance can be an instrumental variable (IV) for attendance in the model of given performance, we need to ensure that it satisfies the following assumptions: Relevance, Exogeneity and Exclusion restriction.

1. Relevance: Distance must be correlated with attendance, meaning that it has a significant effect on attendance. Intuitively, students living closer to the lecture hall may attend classes more frequently.
2. Exogeneity: Distance must not be directly correlated with the error term (u) in the performance equation, meaning that it should not have any direct effect on student performance apart from its impact on attendance. The assumption given already states that distance and u are uncorrelated, which fulfills this requirement.
3. Exclusion restriction: Distance should not have any direct effect on performance except through its influence on attendance. In other words, after controlling for attendance, ACT scores, and GPA, distance should not be a significant predictor of performance.
Additionally, we must assume that there are no other unobserved variables that could be driving the relationship between distance and performance. If these assumptions are met, we can use distance as an instrumental variable to identify the causal effect of attendance on performance.

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In a study done on the life expectancy of 500 people in a certain geographic region, the mean age at death was 72 years and the standard deviation was 5.3 years.If a sample of 50 people from this region is selected, and the probability that the mean life expectancy will be less than 70 years, which of the following will you use?
a.Normal Distribution
b.Central Limit Theorem
c.Discrete Probability Distribution
d.Binomial Distribution​

Answers

b. Central Limit Theorem. in this scenario, we would use the Central Limit Theorem to determine the probability that the mean life expectancy will be less than 70 years.

The Central Limit Theorem states that for a large enough sample size, the sampling distribution of the sample mean will approach a normal distribution, regardless of the shape of the population distribution. In this case, a sample of 50 people is selected, which is reasonably large.

Since the mean and standard deviation of the population are known, we can calculate the z-score for a sample mean of 70 years. The z-score is calculated as:

z = (sample mean - population mean) / (population standard deviation / sqrt(sample size))

= (70 - 72) / (5.3 / sqrt(50))

≈ -1.19

By referring to a standard normal distribution table or using a calculator, we can find the probability of a z-score less than -1.19. This probability corresponds to the probability that the sample mean will be less than 70 years.

Using the Central Limit Theorem, we can approximate the distribution of the sample mean as a normal distribution and calculate the desired probability.

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the number of school districts in the united states is currently approximately (5pts) question 16 - the number of school districts in the united states is currently approximately 73,500 50,000 31,700 15,500

Answers

The number of school districts in the United States is currently approximately 13,500. This answer is option D in the given choices.

The number of school districts in the United States can vary depending on how they are defined, but according to the National Center for Education Statistics (NCES), there were 13,500 public school districts in the U.S. as of the 2018-2019 academic year. These districts serve approximately 50.7 million students in over 98,000 public schools. It is important to note that this number only includes public school districts and does not include private or charter schools.

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\frac{13}{4x-4}=\frac{2}{x-1}+\frac{x+4}{8}

Answers

The given equation is frac{13}{4x-4}=\frac{2}{x-1}+\frac{x+4}{8}. To solve for x, we first simplify the right-hand side by finding a common denominator. Multiplying the second term by frac{2}{2} and the third term by frac{x-1}{x-1}, we get:

frac{13}{4x-4}=\frac{2\cdot 8}{8(x-1)}+\frac{(x+4)(x-1)}{8(x-1)}

Simplifying the right-hand side, we get:

frac{13}{4x-4}=\frac{16}{8(x-1)}+\frac{x^2+3x-4}{8(x-1)}

Combining like terms, we get:

frac{13}{4x-4}=\frac{2x+12+x^2+3x-4}{8(x-1)}

Simplifying, we get:

13(8)=(2x+12+x^2+3x-4)(4x-4)

Expanding the right-hand side and simplifying, we get:

13(8)=4x^3-5x^2-23x+100

This is a cubic equation, which can be solved using various methods such as factoring, the rational root theorem, or numerical methods.

In summary, the given equation frac{13}{4x-4}=\frac{2}{x-1}+\frac{x+4}{8} can be solved by simplifying the right-hand side, combining like terms, and simplifying again to obtain a cubic equation. Various methods can be used to solve the cubic equation and find the value(s) of x.

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If you roll a 6-sided die 6 times, what is the best prediction possible for the number of times you will roll a three?

Answers

Answer: The best prediction possible for the number of times you roll a three is 1/6 of a roll.

Step-by-step explanation:

When you find the statistics of something like rolling a die, you will need to divide how many times you roll the die by how many sides are on the die.

6 - how many times you roll the die

6 - how many sides are on the die

When you divide 6 by 6,  you will get one. Since both of the statistical numbers are the same, you will get an 1/6 chance of rolling a 1, 2, 3, 4, 5, and 6. So 1/6 is the answer! Hope this helps!!!

P.S (I learned this in 5th grade :))

what is the probability that the cost will be less than $240? (round your answer to four decimal places.)

Answers

Without additional information about the distribution of costs, it is impossible to determine the probability that the cost will be less than $240.

To calculate a probability, we need to know the distribution of the data. For example, if the costs followed a normal distribution with a mean of $200 and a standard deviation of $20, we could use a standard normal table or a calculator to find the probability that a randomly selected cost is less than $240.

However, if we do not have information about the distribution of the costs, we cannot calculate a precise probability. In this case, we could make some assumptions about the distribution based on past data or expert opinion and use those assumptions to estimate the probability.

For example, if we know that costs tend to be positively skewed, we might assume that the distribution is lognormal and use that assumption to estimate the probability. Alternatively, we could use a non-parametric method like bootstrapping to estimate the probability based on a sample of observed costs.

Ultimately, the accuracy of any estimate will depend on the quality of the assumptions and the amount of data available.

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Give the slope and the y-intercept of the line y=-6x-2 Make sure the y-intercept is written as a coordinate. This means the y-intercept must be in the form (0,b)

Answers

In summary, the slope of the line is -6, and the y-intercept is (0, -2).

To find the slope and y-intercept of the line y = -6x - 2, we can compare it to the slope-intercept form of a linear equation, which is y = mx + b. In this form, "m" represents the slope, and "b" represents the y-intercept.
For the given equation y = -6x - 2:
1. Identify the slope (m): The coefficient of the x term, which is -6, represents the slope. Therefore, the slope (m) is -6.
2. Identify the y-intercept (b): The constant term, which is -2, represents the y-intercept. To express the y-intercept as a coordinate (0, b), substitute 0 for the x value. So the y-intercept coordinate is (0, -2).
In summary, the slope of the line is -6, and the y-intercept is (0, -2).

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A number cube with the numbers 1 through 6 is rolled. Find the given probability.
1. P(number < 2) (1 point)
A. 1/6 <--- i think this one
B. 2/6
C. 4/6
D. 3/6

Answers

Answer:

P(less than 2) = P(1) = 1/6

A is correct.

The perimeter of a semicircle is 30.84 meters. What is the semicircle's radius?

Answers

Answer:

radius is 6 meters

Step-by-step explanation:

perimeter of semicircle = πr + 2r

πr + 2r = 30.84

3.14r + 2r = 30.84

5.14r = 30.84

r = 30.84 ÷ 5.14

r = 6

Find the equation of the line of best fit for the following data.

x y
3.5 5.85
6.9 1.25
2.1 7.41
0.6 9.73
5.3 3.01
8.2 0.09
4.7 4.62
answer choices:
A. y=-1.2829x+10.3021
B.y=-0.773033x+8.00088
C.y=1.28144x - 1.16414
D. y=-0.252953x + 5.69677

Answers

The line of best fit's equation is as follows:

y = -0.773033x + 8.00088. The answer choice is (B).

The slope of a line is determined by taking the tangent of the angle it forms with the x-axis. The slope of a straight line remains constant over time.

In order to demonstrate the relationship between two variables, linear regression applies a linear equation to the observed data. The idea is that one variable acts as an independent variable and the other as a dependent variable. For instance, a person's weight and height are linearly connected.

To find the equation of the line of best fit, we need to find the slope and y-intercept of the line that minimizes the sum of the squared distances between the line and the data points.

We may determine the slope and y-intercept using linear regression. We obtain the following using a calculator or statistical software:

slope (m) ≈ -0.773033

y-intercept (b) ≈ 8.00088

Thus, the following is the equation for the line of best fit:

y = -0.773033x + 8.00088

So the answer choice is (B).

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