MATH 110 - Introduction to Statistics Module 5, Exams of Mathematics

MATH 110 - Introduction to Statistics Module 5

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2022/2023

Available from 12/21/2023

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MATH 110 - Introduction
to Statistics Module 5
Exam
Exam Page 1
Suppose that you take a sample of size 50 from a population that is not normally distributed. Can the
sampling distribu
ti
on of
x
be approximated by a normal probability distribu
ti
on?
Yes, the sample size can be approximated by a normal probablity ditribution because the sample size is
greater than 30.
Answer Key
Suppose that you take a sample of size 50 from a population that is not normally distributed.
Can the sampling distribu
ti
on of
x
be approximated by a normal probability distribu
ti
on?
Yes. The sample size is greater than 30, therefore, we may approximate by a normal
probability distribution.
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pf4
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MATH 110 - Introduction

to Statistics Module 5

Exam Exam Page 1 Suppose that you take a sample of size 50 from a population that is not normally distributed. Can the sampling distribution of be approximated by a normal probability distribution? Yes, the sample size can be approximated by a normal probablity ditribution because the sample size is greater than 30.

Answer Key

Suppose that you take a sample of size 50 from a population that is not normally distributed.

Can the sampling distribution of x̄ be approximated by a normal probability distribution?

Yes. The sample size is greater than 30, therefore, we may approximate by a normal

probability distribution.

Exam page 3

Suppose that you are attempting to estimate the annual income of 1200 families. In order to

use the infinite standard deviation formula, what sample size, n, should you use?

(n / N ) ≤0.

N = 1200

n ≤ (0.05 x 1200 ) = 60 n ≤ 60 The sample size (n) has to be less than or equal to 60 n ≤ 60 The sample size (n) has to be less than or equal to 60

Answer Key

Suppose that you are attempting to estimate the annual income of 1200 families. In order to

use the infinite standard deviation formula, what sample size, n, should you use?

In order to use infinite standard deviation formula, we should have:

n≤0.05(1200)

n≤

So, the sample size should be less than 60.

Exam Page 4 Suppose that in a very large city 9.8 % of the people have more than two jobs. Suppose that you take a random sample of 70 people in that city, what is the probability that 9 % or more of the 70 have more than two jobs? We want P(Z>-0.23). From the standard normal table, we find: P(Z>-.23)=1- P(Z<-.23)=1-.40905=.59095. So there is a .60257 probability that the percentage of the sample that have more than two jobs is more than 9 %. -1.0 points Instructor Comments The value stated in the conclusion is not correct. Answer Key Suppose that in a very large city 9.8 % of the people have more than two jobs. Suppose that you take a random sample of 70 people in that city, what is the probability that 9 % or more of the 70 have more than two jobs? Now we find the z-score: We want P(Z>-0.23). From the standard normal table, we find: P(Z>-.23)=1- P(Z<-.23)=1-.40905=.59095. So there is a .60257 probability that the percentage of the sample that have more than two jobs is more than 9 %.