Suppose that X is the time it takes a randomly chosen professor in a university department to type and send a standard letter of recommendation for a past student who is applying for a graduate degree program. Suppose X has a normal distribution, and assume the mean is 10.5 minutes and the standard deviation 3 minutes. If you were to take a random sample of 50 professors and measure the time it takes each one of them to type and send such a standard letter of recommendation, what is the probability that their mean time is less than 9.5 minutes?

Answers

Answer 1

Answer:

0.0091 = 0.91% probability that their mean time is less than 9.5 minutes.

Step-by-step explanation:

To solve this question, we need to understand the normal probability distribution and the central limit theorem.

Normal Probability Distribution:

Problems of normal distributions can be solved using the z-score formula.

In a set with mean [tex]\mu[/tex] and standard deviation [tex]\sigma[/tex], the z-score of a measure X is given by:

[tex]Z = \frac{X - \mu}{\sigma}[/tex]

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the p-value, we get the probability that the value of the measure is greater than X.

Central Limit Theorem

The Central Limit Theorem estabilishes that, for a normally distributed random variable X, with mean [tex]\mu[/tex] and standard deviation [tex]\sigma[/tex], the sampling distribution of the sample means with size n can be approximated to a normal distribution with mean [tex]\mu[/tex] and standard deviation [tex]s = \frac{\sigma}{\sqrt{n}}[/tex].

For a skewed variable, the Central Limit Theorem can also be applied, as long as n is at least 30.

The mean is 10.5 minutes and the standard deviation 3 minutes.

This means that [tex]\mu = 10.5, \sigma = 3[/tex]

Sample of 50:

This means that [tex]n = 50, s = \frac{3}{\sqrt{50}}[/tex]

What is the probability that their mean time is less than 9.5 minutes?

This is the pvalue of Z when X = 9.5. So

[tex]Z = \frac{X - \mu}{\sigma}[/tex]

By the Central Limit Theorem

[tex]Z = \frac{X - \mu}{s}[/tex]

[tex]Z = \frac{9.5 - 10.5}{\frac{3}{\sqrt{50}}}[/tex]

[tex]Z = -2.36[/tex]

[tex]Z = -2.36[/tex] has a pvalue of 0.0091

0.0091 = 0.91% probability that their mean time is less than 9.5 minutes.


Related Questions

Need help with Algebra 2! Thank you! :)

Answers

Answer:

Consider the parent logarithm function f(x) = log(x)

Now,

Let us make transformations in the function f(x) to get the function g(x)

•On streching the graph of f(x) = log(x) , vertically by a factor of 3, the graph of y = 3log(x) is obtained.

•Now, shrinking the graph of y = 3log(x) horizontally by a fctor of 2 to get the grpah of y = 3log(x/2) i.e the graph of g(x)

Hence, the function g(x) after the parent function f(x) = log(x) undergoes a vertical stretch by a factor of 3, and a horizontal shrink by a factor of 2 is

g(x) = 3 log(x/2) (Option-B).

Can I have some help

Answers

itd be 1, because the other ones aren’t possible

The number of light bulbs produced by a company can be modeled by the expression
15x^3+16x^2–100x+51, where x is the number of years passed since 1980. The number of companies
purchasing the light bulbs is represented by 5x–3. Which is the expression representing the average number
of light bulbs purchased per company?

Answers

Answer:

Expression is 3x² + 5x - 17

Step-by-step explanation:

We are told the number of lights produced by a company is;

Number of lights = 15x^3 + 16x^2 – 100x + 51

Also, number of companies that purchased the light bulbs is 5x - 3.

Thus;

The average number of bulbs purchased per company = (15x^3 + 16x^2 – 100x + 51)/(5x - 3)

I have attached the calculation using long division method to get;

3x² + 5x - 17

Which rule describes the x-coordinates in the translation below?.

O x + 0
O x + 6
O x-6
O X+2

Answers

i think it would be x+2

if each quadrilateral below is a square, find the missing measures.

please help :(

Answers

vu=15 su=square root 450 TV= square root 450 SW= squareroot 450/2

We want to find the missing measures for the given square.

VU = 15TV = 21.2SU = 21.2SW = 10.6

Working with squares.

We know that squares have the same length in all of their 4 sides, with that in mind we can see that:

TS = TU = UV = SV = 15

Then we can already complete:

VU = 15

Now we need the two diagonals, SU and TV.

The diagonal for a square of side length s is:

diagonal = (√2)s

Then the diagonals for our square are:

TV = SU = (√2)*15 = 21.2

And SW is half of the diagonal, so we have:

SW = 21.2/2 = 10.6

If you want to learn more about squares, you can read:

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Evie buys an energy drink
The can is 12 cm high and the diameter is 5 cm.
Use 1-3
+5 cm
12 cm
SINH
Using the formula V = 12h, work out the volume of the can.
Give the units of your answer.
Select...

Answers

ngl I think you'll have to format it clearer, cause I have no clue what's happening

A cone has a height of 7.25 cm and a base with a radius of 4.5 cm.
What is the approximate volume of the cone?
A. 32.63 cm
B. 102.44 cm
C. 146.81 cm3
D. 153.66 cm3

Answers

Answer:

v=1\3hπr3

Step-by-step explanation:

1/3×,22/7×4.5×4.5××7.25

=153.66cm3

1. What is the probability that three or more copies will be demanded in a particular day?
a. 0.14
b. 0.20
c. 0.64
d. 1

Answers

Answer:

C. 0.64

Step-by-step explanation:

Sana makatulong :-)

Instructions require you to dilute a powder in 3 quarts of water. You only have a container that is marked in liters. How many liters would you use to dilute the powder?

Answers

Answer:

1 quart = .947 L

3 Q = 2.841 L

So you should use 2.841 L to dissolve the powder

One quartz is equal to 32 oz, then 2.88 liters of water are used to dilute the powder.

What is a conversion of units?

The unit conversion deals with the operation to change one form of the unit to another form of unit.

Instructions require you to dilute a powder in 3 quarts of water. You only have a container that is marked in liters.

We know that

1 quartz = 32 oz

3 quartz = 96 oz

Since 30 milliliters per oz

Then

30 milliliters × 96 oz = 2880 milliliters

Since 1000 milliliters per liter, then we have

[tex]\rm \dfrac{2880}{1000}=2.88\ liters[/tex]

2.88 liters are used to dilute the powder.

More about the conversion of a unit link is given below.

https://brainly.com/question/655411

Kevin can paint a small room in 18 hours. Kevin and Caleb together can paint the same room in 15 hours.
How long would it take for Caleb to paint the room alone?

Answers

Answer:

90 hours

Step-by-step explanation:

The computation of the time taken for Caleb to paint the room alone is given below:

Given that

Kevin paint a small room in 18 hours

And, kevin & caleb together paint the same room in 15 hours

So, time taken for Caleb to paint the room alone is

Let us assume the same be x

Kevin time taken + caleb time taken = total time taken

[tex]\frac{1}{18} + \frac{1}{x} = \frac{1}{15}\\\\ \frac{1}{x} = \frac{1}{15} - \frac{1}{18}\\\\ \frac{1}{x} = \frac{6-5}{90} \\\\ \frac{1}{x} = \frac{1}{90}[/tex]

x = 90 hours

If anyone knows this I will give them brainiest

Answers

Answer:

x = 12

m(QS) = 52°

m(PD) = 152°

Step-by-step explanation:

Recall: Angle formed by two secants outside a circle = ½(the difference of the intercepted arcs)

Thus:

m<R = ½[m(PD) - m(QS)]

50° = ½[(12x + 8) - (4x + 4)] => substitution

Solve for x

Multiply both sides by 2

2*50 = (12x + 8) - (4x + 4)

100 = (12x + 8) - (4x + 4)

100 = 12x + 8 - 4x - 4 (distributive property)

Add like terms

100 = 8x + 4

100 - 4 = 8x

96 = 8x

96/8 = x

12 = x

x = 12

✔️m(QS) = 4x + 4 = 4(12) + 4 = 52°

✔️m(PD) = 12x + 8 = 12(12) + 8 = 152°

Please help solve, 7th grade work (see image)

Answers

Answer:

F) 63

Step-by-step explanation:

Find the original total stories 10 + 8 + 16 + 8 = 42.

Original ratio of Mary's stories to total stories is 8/42 or 4/21.

Then form equation 4/21 = 12/x ; multiply both sides of 4/21 by 3.

4/21 = 12/63

The students need to write 63 stories to keep the ratio of Mary's stories to total stories the same.

17-3/4 17-3/4 just that​

Answers

Answer: 264.0625

Step-by-step explanation:

let me know if im wrong

What is the product of 2.8 and 2.9? a.) 0.618 b.) 6.18 c.) 9.512 d.) 3.608​

Answers

Answer:

its a

Step-by-step explanation:

Solve the equation below, remember to check for extraneous solutions.

Answers

Answer:

2.66x + 18 = -3

Step-by-step explanation:

X=27?54?61
Hellpppp plz only serious answers

Answers

Answer: I’m pretty sure your right

Step-by-step explanation:

sorry if I’m wrong

Answer:

You are right

Step-by-step explanation:

solve 7x+4/3x+2= -4/3​

Answers

Answer:

7x+4/3x+2= -4/3 don't know

suppose f(×) = 2^×, sketch a graph of f(×) and f^-1(×)​

Answers

Let f(x) = y

y = 2^x

x = 2^y

Solve for y.

ln x = ln(2^y)

ln x = y ln 2

ln x/ln 2 = y

Replace y with f^(-1) x.

f^(-1) x = ln x/ln 2

We now know f(x) and f^(-1) x.

Use your graphing calculator to graph the function and its inverse on the same xy-plane. If you don't have a graphing calculator, use DESMOS online.

Good luck.  

Need help on this please still lost on this

Answers

Step-by-step explanation:

Area of Circle =

[tex]\pi {r}^{2} \\ = \pi {(4)}^{2} \\ = 16\pi {km}^{2} [/tex]

answer..................

If Jeffrey invested $2,000 (principal) for 5 years at 5% interest rate compounded annually how much Interest would he earn over 5 years?

Answers

Answer:

Total = principal * (1+ rate/100)^ years

Total = 2,000 * 1.05^5

Total = 2,000 * 1.2762815625

Total = 2,552.36

Source: http://www.1728.org/compint2.htm

Step-by-step explanation:

Please help I’ll mark you as brainliest if correct!

Answers

Answer:

the anwer is C.

Step-by-step explanation:

Answer:

190.50

Step-by-step explanation: 6 ft. 3in divided by 2.54

Hi help pls and ty no link pls

Answers

Answer:

3.141

Step-by-step explanation:

just find area of full circle which is 12.566 then divide by 4 (its pi)

Answer:

3.14x2

Step-by-step explanation:

Can someone please help me sorry it’s kinda hard to see

Answers

Answer:

C.

Step-by-step explanation:

each edge/vertex was taken 2 units to the right and 8 units down to make the figure M'

I traced it to make sure

hope this helps <3

Answer:

C.

Step-by-step explanation:

each edge/vertex was taken 2 units to the right and 8 units down to make the figure M'

I traced it to make sure

hope this helps <3

a builder has built 1/6 of the floors of a new skyscraper. If the builder has built 13 floors, how many floors will the skyscraper have when it is finished? Write and solve an equation to find the answer.

Answers

Answer: 78 floors total

Step-by-step explanation:

if 13=1/6

6 x 13=78

Answer:

13*6=78

Step-by-step explanation:

If one part of something is equal to 13, then 6 parts are equal to 13*6. Let us denote that "something" by x, and we get

[tex]x = 6 \times \frac{1}{6} x = 6 \times 13[/tex]

Which is obviously an identity

What is 468,839 rounded to the nearest hundred thousand?

Answers

Answer:

500,000

Step-by-step explanation:

Answer:

500,000

hope this is right

What is the right answer?? Please tell meeee

Answers

Answer:

2\sqrt{x}+\frac{1}{2\sqrt{x}}\left(2x+3\right)

Step-by-step explanation:

which is D on your phone

10 POINT PLEASE HELP ME

Answers

Answer:

9.0

Step-by-step explanation:

A box contains 16 chocolates, of which
3 are known to contain nuts.
Two chocolates are selected at random.
a. Find the probability that
a exactly one chocolate contains
nuts

b at least one chocolate contains
nuts.

Answers

Answer:

3/16??? and 1/16???

Step-by-step explanation:

im so sorry this might be wrong

The probability that a exactly one chocolate contains nuts is 3/16 and probability that at least one chocolate contains nuts is 0.339.

How to calculate probability ?

Probability is calculated by dividing the number of possible outcomes by the total number of possible outcomes. Probability and odds are two distinct concepts. Odds are calculated by dividing the probability of something happening by the probability of it not happening.

When you calculate probability, you are estimating the likelihood of something occurring and representing it with a precise number.

The probability that a exactly one chocolate contains nuts

No of total chocolates = 16 chocolates

No of chocolates contain nuts = 3

The probability that a exactly one chocolate contains nuts = 3/16

Probability that  at least one chocolate contains nuts is

P(at least one contains nut) = 1 – P(given contains no nuts )^n

P(at least one contains nut) = 1 – (0.8125)^2

P(at least one contains nut) = 0.339

Probability that  at least one chocolate contains nuts = 0.339

To learn more about Probability refer :

https://brainly.com/question/251701

#SPJ2

50 POINTS
NO LINKS
WILL MARK BRAINLYEST ​

Answers

The equation is 7=1x and answer x=7

My mother is 43 years old.I am w years old. Write an expression as to how old we will both be in h year's time.​

Answers

Answer:

W+h=         43+h=

Step-by-step explanation:

THis shows your age plus h the amount of years time. the second expression represents your mothers age plus h.

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