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Body Mass Index. Body mass index (BMI) is a measure of body fit based on height and weight. According to the document Dietary Guidelines for Americans, published by the U.S. Department of Agriculture and the U.S. Department of Health and Human Services, for adults, a BMI of greater than 25 indicates an above healthy weight (i.e., overweight or obese), Oct 750 randomly selected adults whose highest degree is a bachelor's, 386 have an above healthy weight; and of 500 randomly selected adults with a graduate degree, 237 have an above healthy weight.

a. What assumptions are required for using the two-proportions z-lest here?

b. Apply the two-proportions z-test to determine, at the 5% significance level, whether the percentage of adults who have an above healthy weight is greater for those whose highest degree is a bachelor's than for those with a graduate degree.

Short Answer

Expert verified

a) The assumptions of the two proportions are satisfied.

b) There is no evidence to infer that the percentage of adults who have an above healthy weight is greater for those whose highest degree is a bachelor's than for those with a graduate degree.

Step by step solution

01

Part(a) Step 1: Given Information

The given values are,

x1=386,n1=750,x2=237,n2=500,α=0.05

02

Part(a) Step 2: Explanation

The formula for p~1is given by,

p~1=x1n1

The formula for p~2is given by,

p~2=x2n2

The formula forzis given by,

z=p~1-p~2p~p1-p~p1n1+Γm2

The formula forp~pis given by,

p~p=x1+x2n1+n2

The value ofn1-x1is calculated as,

n1-x1=2701-35=2666

The value ofn2-x2is calculated as,

n2-x2=2052-47=2005

The values x1,n1-x1,x2, and n2-x2are all greater than 5 .

The value ofp~1is calculated as,

p~1=x1n1=386750=0.514\

The value of p~2is calculated as,

p~2=x2n2=237500=0.474

The value of p~pis calculated as,

p~p=x1+x2n1+n2=386+237750+500=0.4984

Assumptions:

The selected sample should be a simple random sample from two populations.

The samples are independent of one another.x1,n1-x1,x2and n2-x2are all at least 5.

The two samples are random samples, the sample is independent of each other and thex1,n1-x1,x2 andn2-x2 are all at least 5 .

Therefore, the assumptions for two proportions are satisfied.

03

Part(b) Step 1: Given Information

The given values are,

x1=386,n1=750,x2=237,n2=500,α=0.05

04

Part(b) Step 2: Explanation 

The null hypothesis:

H0:p1>p2

The alternative hypothesis:

Ha:p1>p2

Using the MINITAB output.

MINITAB output: Test and Cl for two proportions.

From MINITAB output, the test statistic is 1.41and p-value is 0.079

p- value is greater than the level of significance.

p- value(=0.079)>α(=0.05).

The null hypothesis is rejected.

There is no evidence to suggest that those with a bachelor's degree have a higher percentage of adults who are overweight than those with a graduate degree.

As a result, there is no evidence to suggest that those with a bachelor's degree have a higher percentage of adults who are overweight than those with a graduate degree.

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Most popular questions from this chapter

Margin of error=0.02

Confidence level=90%

Educated guess=0.1

(a) Obtain a sample size that will ensure a margin of error of at most the one specified (provided of course that the observed value of the sample proportion is further from 0.5that of the educated guess.

(b). Compare your answer to the corresponding one and explain the reason for the difference, if any.

Obtain a sample size

Margin of error =0.02

Confidence level =95%

Likely range 0.4-0.7

We have given a likely range for the observed value of a sample proportion p^

0.7orless

a. Based on the given range, identify the educated guess that should be used for the observed value of p^to calculate the required sample size for a prescribed confidence level and margin of error.

b. Identify the observed values of the sample proportion that will yield a larger margin of error than the one specified if the educated guess is used for the sample-size computation.

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a. At the 5%significance level, do the data suggest that there is a difference between the labor-force participation rates of U.S. and Canadian women?

b. Find and interpret a 95% confidence interval for the difference between the labor-force participation rates of U.S. and Canadian women.

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b. Identify the observed values of the sample proportion that will yield a larger margin of error than the one specified if the educated guess is used for the sample-size computation.

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