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3 years ago

PLEASE HELP!!!!!!! WILL GIVE BRAINLIEST!!!!!! PLEASE!!!

Mathematics

1 answer:

White raven [17]3 years ago

8 0

Answer:

sorry can't answer u have to many tabs open

Step-by-step explanation:

slowly start to take away your tabs

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Time spent using e-mail per session is normally distributed, with mu equals 11 minutes and sigma equals 3 minutes. Assume that

liq [111]

Answer:

a) 0.259

b) 0.297

c) 0.497

Step-by-step explanation:

To solve this problem, it is important to know the normal probability distribution and the central limit theorem.

Normal probability distribution

Problems of normally distributed samples are solved using the z-score formula.

In a set with mean $\mu$ and standard deviation $\sigma$ , the zscore of a measure X is given by:

$Z = \frac{X - \mu}{\sigma}$

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 pvalue, 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 random variable X, with mean $\mu$ and standard deviation $\sigma$ , a large sample size can be approximated to a normal distribution with mean $\mu$ and standard deviation $s = \frac{\sigma}{\sqrt{n}}$

In this problem, we have that:

$\mu = 11, \sigma = 3$

a. If you select a random sample of 25 sessions, what is the probability that the sample mean is between 10.8 and 11.2 minutes?

Here we have that $n = 25, s = \frac{3}{\sqrt{25}} = 0.6$

This probability is the pvalue of Z when X = 11.2 subtracted by the pvalue of Z when X = 10.8.

X = 11.2

$Z = \frac{X - \mu}{\sigma}$

By the Central Limit Theorem

$Z = \frac{X - \mu}{s}$

$Z = \frac{11.2 - 11}{0.6}$

$Z = 0.33$

$Z = 0.33$ has a pvalue of 0.6293.

X = 10.8

$Z = \frac{X - \mu}{s}$

$Z = \frac{10.8 - 11}{0.6}$

$Z = -0.33$

$Z = -0.33$ has a pvalue of 0.3707.

0.6293 - 0.3707 = 0.2586

0.259 probability, rounded to three decimal places.

b. If you select a random sample of 25 sessions, what is the probability that the sample mean is between 10.5 and 11 minutes?

Subtraction of the pvalue of Z when X = 11 subtracted by the pvalue of Z when X = 10.5. So

X = 11

$Z = \frac{X - \mu}{s}$

$Z = \frac{11 - 11}{0.6}$

$Z = 0$

$Z = 0$ has a pvalue of 0.5.

X = 10.5

$Z = \frac{X - \mu}{s}$

$Z = \frac{10.5 - 11}{0.6}$

$Z = -0.83$

$Z = -0.83$ has a pvalue of 0.2033.

0.5 - 0.2033 = 0.2967

0.297, rounded to three decimal places.

c. If you select a random sample of 100 sessions, what is the probability that the sample mean is between 10.8 and 11.2 minutes?

Here we have that $n = 100, s = \frac{3}{\sqrt{100}} = 0.3$

This probability is the pvalue of Z when X = 11.2 subtracted by the pvalue of Z when X = 10.8.

X = 11.2

$Z = \frac{X - \mu}{\sigma}$

By the Central Limit Theorem

$Z = \frac{X - \mu}{s}$

$Z = \frac{11.2 - 11}{0.3}$

$Z = 0.67$

$Z = 0.67$ has a pvalue of 0.7486.

X = 10.8

$Z = \frac{X - \mu}{s}$

$Z = \frac{10.8 - 11}{0.3}$

$Z = -0.67$

$Z = -0.67$ has a pvalue of 0.2514.

0.7486 - 0.2514 = 0.4972

0.497, rounded to three decimal places.

5 0

3 years ago

What numbers do you need to determine the surface area of a right cone? ANSWERS: The radius of the base, r, and the altitude h.

tiny-mole [99]

Answer:

The Radius of the base, r, and the altitude h

Step-by-step explanation:

Surface area of a right cone

$a=\pi r\sqrt{h^{2}+r^{2} }$

R= Radius

H=Radius

7 0

3 years ago

Simplify the expression.<br><br> 2+22÷4+3

Dmitrij [34]

Answer:

The answer is 10.5

Step-by-step explanation:

6 0

3 years ago

A farmer decides to enclose a rectangular garden, using the side of a barn as one side of the rectangle. What is the maximum are

kifflom [539]

Garden
max area is if the sides are as equal as possible
so he should try to make a square (ideal is a circle, but barn walls are normally straight)
squaer perimiter=4 times legnth of 1 side
perimiter=amount of fencing=80
80=4s
divide 4
20=s
one sides=20

area=legnth times width
in squaer, legnth=width

20=legnth
20=width
area=20 times 20=400

dimetions are 20ft by 20ft to give 400ft^2
(fun fact, if it were a circle, the area would be about 509.5ft^2)

answer is 20ft by 20ft and area=400ft^2

7 0

3 years ago

Jennifer and Callie are training for a marathon. Jennifer has run m miles, and Callie has run 3 times as many as Jennifer. The e

galben [10]

What’s the question,

4 0

3 years ago

Read 2 more answers