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Chapter 7 - Practice Problems 1

SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question.

Provide an appropriate response.

1) Define a point estimate. What is the best point estimate for ? 1)

2) Define margin of error. Explain the relation between the confidence interval and the error

estimate. Suppose a confidence interval is 9.65 <

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Solve the problem.

9)

^

The following confidence interval is obtained for a population proportion, p:

(0.700, 0.728)

Use these confidence interval limits to find the point estimate, p .

9)

A) 0.718 B) 0.714 C) 0.728 D) 0.700

10) The following confidence interval is obtained for a population proportion, p:0.478

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Solve the problem.

19) Find the point estimate of the true proportion of people who wear hearing aids if, in a random

sample of 496 people, 73 people had hearing aids.

19)

A) 0.128 B) 0.853 C) 0.147 D) 0.145

20) 50 people are selected randomly from a certain population and it is found that 13 people in the

sample are over 6 feet tall. What is the point estimate of the true proportion of people in the

population who are over 6 feet tall?

20)

A) 0.50 B) 0.74 C) 0.26 D) 0.19

Use the given degree of confidence and sample data to construct a confidence interval for the population proportion p.

21) A survey of 865 voters in one state reveals that 408 favor approval of an issue before the legislature.

Construct the 95% confidence interval for the true proportion of all voters in the state who favor

approval.

21)

A) 0.438

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Use the confidence level and sample data to find the margin of error E.

27) Weights of eggs: 95% confidence; n = 52,x = 1.78 oz, = 0.40 oz 27)

A) 0.02 oz B) 0.11 oz C) 0.09 oz D) 7.21 oz

28) Systolic blood pressures for women aged 18- 24: 94% confidence; n = 98,x = 113.1 mm Hg,

= 13.4 mm Hg

28)

A) 50.3 mm Hg B) 9.9 mm Hg C) 2.2 mm Hg D) 2.5 mm Hg

Use the confidence level and sample data to find a confidence interval for estimating the population .

29) Test scores: n = 95, x = 73.8, = 7.4; 99 percent 29)

A) 72.5 < < 75.1 B) 71.8 < < 75.8 C) 72.3 < < 75.3 D) 72.0 < < 75.6

30) A random sample of 194 full- grown lobsters had a mean weight of 21 ounces and a standard

deviation of 3.8 ounces. Construct a 98 percent confidence interval for the population mean .

30)

A)20