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Chapter 9: Q.100 (page 553)

According to an article in Bloomberg Businessweek, New York City's most recent adult smoking rate is 14%. Suppose that a survey is conducted to determine this year’s rate. Nine out of 70 randomly chosen N.Y. City residents reply that they smoke. Conduct a hypothesis test to determine if the rate is still 14% or if it has decreased.

Short Answer

Expert verified

Confidence Interval: (0.0502, 0.2070)

Step by step solution

01

Find H0 and Ha: We want to test if New York City (NYC) adults take less than 14% of them to smoke, on average.

H0:p=0.14;Ha:p<0.14

02

Determine the distribution needed: In words, CLEARLY state what your random variable P′ represents.Let P′ = the proportion of NYC residents that smoke.

Normal:N0.14,(0.14)(1-0.14)70

Test Statistic:z=–0.2756

03

Calculate the p-value using the normal distribution for proportions:

p-value=0.3914

In one to two complete sentences, explain what the p-value means for this problem.

If the null hypothesis is true (the proportion is 0.14), then there is a 0.3914 probability that the sample (estimated) proportion is 0.129 or more.

04

Compare α and the p-value:Indicate the correct decision (“reject” or “do not reject” the null hypothesis), the reason for it, and write an appropriate conclusion, using complete sentences.

alphadecisionreason for decision
0.05Do not reject the null hypothesis.
p-value>0.05

Conclusion: At the 5% significance level, there is insufficient evidence to conclude that the proportion of NYC residents who smoke is less than 0.14.

05

Confidence Interval

Confidence Interval: (0.0502, 0.2070): The “plus-4s” confidence interval (see chapter 8) is (0.0676, 0.2297).

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Most popular questions from this chapter

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"Dalmatian Darnation," by Kathy Sparling

A greedy dog breeder named Spreckles

Bred puppies with numerous freckles

The Dalmatians he sought

Possessed spot upon spot

The more spots, he thought, the more shekels.

His competitors did not agree

That freckles would increase the fee.

They said, “Spots are quite nice

But they don't affect price;

One should breed for improved pedigree.”

The breeders decided to prove

This strategy was a wrong move.

Breeding only for spots

Would wreak havoc, they thought.

His theory they want to disprove.

They proposed a contest to Spreckles

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They averaged ninety six dots

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Based on all the dog data they've got?
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