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In 2007, 50% of Americans said they did not trust the media. In a 2017 poll of 5

ID: 3229441 • Letter: I

Question

In 2007, 50% of Americans said they did not trust the media. In a 2017 poll of 572 adults nationwide, 248 stated they did not trust the media. At the alpha equals 0.10 level of significance, is there evidence to support the claim that the percentage of Americans that do not trust the media to report fully and accurately has decreased since 2007?

Which of the following is the best to describe the test?

A. One sample proportion, left-tailed, t-test

B. One sample proportion, right-tailed, z-test

C. One sample mean, left-tailed, z-test

D. One sample proportion, left-tailed, z-test

E. One sample mean, right-tailed, t-test

What will be the test hypotheses?

A. H0: p=0.5 vs H1: p<0.5

B. H0: p=0.5 vs H1: p>0.5

C. H0: p=0.5 vs H1: p0.5

D. H0: µ(M-P)0 vs H1: µ(M-P)=0

E. H0: µ(M-P)0 vs H1: µ(M-P)=0

What is the critical value in the test?

A. -1.5379

B. -1.2816

C. -1.7942

D. -2.0505

E. -0.7689

What is the test statistic in the test?

A. -3.1677

B. -3.1777

C. -3.0677

D. -3.2877

E. -2.9677

What should we do about the hypotheses?

A. Do not reject the alternative hypothesis.

B. Accept both hypotheses.

C. Reject the null hypothesis.

D. Accept the null hypothesis.

E. Reject both hypotheses.

What is the research conclusion?

A. There is sufficient evidence to conclude that the average of Americans that do not trust the media was not 50%.

B. There is sufficient evidence to conclude that the percentage of Americans that do not trust the media was decreaded.

C. There is insufficient evidence to conclude that the average percentage of Americans that do not trust the media was 50%.

D. There is sufficient evidence to conclude that the average age of a mother at the time of her first childbirth was not 50%.

E. There is sufficient evidence to conclude that the percentage of Americans that do not trust the media was not decreased.

Compute the upper boundary of the 97% C.I. for the estimated population proportion.

A. 0.4789

B. 0.4589

C. 0.5989

D. 0.3589

Explanation / Answer

C. One sample mean, left-tailed, z-test as we need to check the claim of decrease and also np>5

Test hypothesis will be

A. H0: p=0.5 vs H1: p<0.5

For alpha =0.10

Critical value is

B. -1.2816

Test statistics is

z=(phat-p)/SEp

Where SEp=sqrt(pq/n)=0.02 & phat=0.43

Hence z=(0.43-0.5)/0.02=-3.1777 i.e B

As z critical > a statistics we reject the null hypothesis

C. Reject the null hypothesis.

As per alternative hypothesis

answer is

B. There is sufficient evidence to conclude that the percentage of Americans that do not trust the media was decreaded.

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