suppose that from the past experience a professor knows that the test score of a student taking his final examination is a random variable with mean 60 and standard deviation 8. how many students would have to take the examination to ensure, with probability at least 0.94 , that the class average would be within 2 of 60 ?

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Answer 1

We need at least 26 students to take the examination to ensure, with probability at least 0.94, that the class average will be within 2 of 60.

What will be the test score of a student?

Let X be the test score of a student. We know that X is a random variable with mean μ = 60 and standard deviation σ = 8.

We want to find the sample size n required to ensure, with probability at least 0.94, that the sample mean (i.e., class average) is within 2 of 60. In other words, we want to find n such that:

P(|sample mean - μ| < 2) ≥ 0.94

The sample mean is a random variable as well, with mean μ and standard deviation σ/sqrt(n) (by the Central Limit Theorem).

Using the standard normal distribution, we can rewrite the above inequality as:

P(-2sqrt(n)/8 < Z < 2sqrt(n)/8) ≥ 0.94

where Z is the standard normal random variable. We can use a standard normal table or a calculator to find the corresponding values of -2sqrt(n)/8 and 2sqrt(n)/8.

We can simplify the inequality as follows:

P(Z < 2sqrt(n)/8) - P(Z < -2sqrt(n)/8) ≥ 0.94

Using a standard normal table or calculator, we find that P(Z < 2.11) ≈ 0.9838 and P(Z < -2.11) ≈ 0.0162. Therefore, we can rewrite the inequality as:

0.9838 - 0.0162 ≥ 0.94

Simplifying, we get:

0.9676 ≥ 0.94

This is true, so we have found the required value of n. To find n, we solve for sqrt(n):

2.11 = 2sqrt(n)/8

Multiplying both sides by 8 and squaring, we get:

n = (8*2.11/2)^2 = 25.67

Rounding up to the nearest integer, we get n = 26.

Therefore, we need at least 26 students to take the examination to ensure, with probability at least 0.94, that the class average will be within 2 of 60.

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Related Questions

Ari plays an online game that charges his debit card $16 per month. Which integer represents the change in Ari’s balance in dollars after paying to play the game for 3 months? Multiple choice question. cross out A)

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Answer: The answer is A -48 dollars

Step-by-step explanation: you times 16 by 3 which make 48 and since its debt you take away so thats negative 48

#9Change from standard form to vertex formy= -xÂ²+4x-1

Answers

So the vector form of the equation is: y = -1(x - 2)² + 3.

To convert from standard form to vertex form, we complete the square by following these steps:

Factor out the coefficient of the x-squared term:

y = -x² + 4x - 1

= -1(x² - 4x) - 1

To complete the square inside the parentheses, add and subtract the square of half of the coefficient of the x-term (-4/2)^2 = 4:

y = -1(x² - 4x + 4 - 4) - 1

Simplify the expression inside the parentheses by factoring a perfect square:

y = -1((x - 2)² - 4) - 1

Distribute the -1 and simplify:

y = -1(x - 2)² + 3

Therefore, the vertex of the parabola is at (2, 3), and the negative coefficient of the x-squared term means that the parabola opens downwards.

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You buy one container each of strawberries,
blueberries, and cherries. Cherries are $1 more per container than blueberries, which are $1 more per container than strawberries. The product of the 3 individual prices is 5 times the total cost of one container of each fruit.
a. Write a polynomial function to model the cost of your purchase.

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Answer: its 7 i took the quiz

g if k < n - r, the value of max value(r, 0, k) should be the larger of two expressions. one of these expressions has -1 as the second parameter to maxvalue. what is it?

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The larger of the two expressions is maxvalue(r, n - k - r, k).

The expression with -1 as the second parameter to maxvalue is maxvalue(n-k-r, -1, k).

To see why this is the case, let's consider the definition of maxvalue(r, a, b). This function returns the maximum value among r, a, and b.

Now, suppose that k < n - r. Then, we have:

n - k - r > n - (n - r) - r = r

This means that n - k - r is greater than r, so maxvalue(r, n - k - r, k) will return either n - k - r or k, whichever is greater.

On the other hand, since -1 is less than any non-negative integer, we have:

-1 < 0 <= r

Therefore, maxvalue(r, -1, k) will return either r or k, whichever is greater.

Since r is non-negative, we have:

maxvalue(r, -1, k) = max(r, -1, k) = max(r, k)

So, the larger of the two expressions is maxvalue(r, n - k - r, k).

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Use a triple integral to find the volume of the given solid.The solid enclosed by the paraboloidsy = x2 + z2andy = 72 − x2 − z2.

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The volume of the given solid enclosed by the paraboloids y = x2 + z2andy = 72 − x2 − z2 is 10368 cubic units.

Using a triple integral, we will integrate over the region of the xz-plane that is enclosed by the paraboloids.

The limits of integration for x and z can be found by solving the two equations for x^2 + z^2:

$x^2 + z^2 = y = x^2 + z^2 + 72 - x^2 - z^2$

$x^2 + z^2 = 36$

Therefore, the limits of integration for x and z are from -6 to 6.

The limits of integration for y are from the equation of the lower paraboloid $y = x^2 + z^2$ to the equation of the upper paraboloid $y = 72 - x^2 - z^2$.

Therefore, the limits of integration for y are from $x^2 + z^2$ to $72 - x^2 - z^2$.

The triple integral for the volume of the solid is:

$\iiint_V dV = \int_{-6}^{6} \int_{-6}^{6} \int_{x^2+z^2}^{72-x^2-z^2} dy dz dx$

Integrating with respect to y:

$\int_{x^2+z^2}^{72-x^2-z^2} dy = 72 - 2(x^2 + z^2)$

Substituting this into the triple integral gives:

$\iiint_V dV = \int_{-6}^{6} \int_{-6}^{6} (72 - 2(x^2 + z^2)) dz dx$

Integrate with respect to z:

$\int_{-6}^{6} (72 - 2(x^2 + z^2)) dz = 72(12) - 4x^2(6) = 864 - 24x^2$

Integrate with respect to x:

$\int_{-6}^{6} (864 - 24x^2) dx = 2(864)(6) - 2\int_{0}^{6} (24x^2) dx = 10368$

Therefore, the volume of the solid enclosed by the paraboloids $y = x^2 + z^2$ and $y = 72 - x^2 - z^2$ is 10368 cubic units.

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Find the exact value of sin 4π/3 using both double and half angle identities.

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The exact value of sin 4π/3 using both double and half angle identities is: -¹/₂√3

How to use Trigonometric Identities?

Trigonometric Identities are defined as the equalities that involve trigonometry functions and holds true for all the values of variables given in the equation. There are various distinct trigonometric identities involving the side length as well as the angle of a triangle.

Using the trigonometric identity: sin 2A = 2sin A cos A

Thus:

sin 2(2π/3) = 2 sin (2π/3) cos (2π/3)

From trigonometric tables, we have:

= 2((√3)/2 * -1/2)

= -¹/₂√3

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what is the greatest three-digit positive integer n for which the sum of the first n positive integers is not a divisor of the product of the first n positive integers? (2019 amc 10a problem 9) (a) 995 (b) 996 (c) 997 (d) 998 (e) 999

Answers

The largest three-digit positive integer n for which the sum of the first n positive integers is not a divisor of the product of the first n positive integers is 995.

We have,

To solve this problem, let's consider the sum and the product of the first n positive integers separately.

The sum of the first n positive integers can be expressed as:

S = 1 + 2 + 3 + ... + n = (n(n+1))/2.

The product of the first n positive integers can be expressed as:

P = 1 x 2 x 3 x ... x n = n!.

We want to find the largest three-digit positive integer n for which S is not a divisor of P.

Since P = n! grows faster than S = (n(n+1))/2, we need to find a value of n where P is not divisible by S.

By observing the answer choices, we can start from the largest answer choice and work our way down until we find a value where P is not divisible by S.

Let's test the values of n given in the answer choices:

For n = 999:

P = 999! and S = (999(999+1))/2 = 499500.