NEED THESE TO BE DONE AND SENT BCK IN 20 HRS

MAT 181 Chapter 7 Practice Problems -Q

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Proportion:

Express the confidence interval using the indicated format.

1) Express the confidence interval 0.039 < p < 0.479 in the form of

± E.

Solve the problem. Round the point estimate to the nearest thousandth.

2) Find the point estimate of the proportion of people who wear hearing aids if, in a random sample of 898 people, 46 people had hearing aids.

Solve the problem.

3) The following confidence interval is obtained for a population proportion, p: 0.537 < p < 0.563. Use these confidence interval limits to find the point estimate,

.

Find the indicated critical z value.

4) Find the critical value

that corresponds to a 91% confidence level.

5) Find

for α = 0.12.

Assume that a sample is used to estimate a population proportion p. Find the margin of error E that corresponds to the given statistics and confidence level. Round the margin of error to four decimal places.

6) 99% confidence; n = 6500, x = 1950

7) In a random sample of 184 college students, 97 had part-time jobs. Find the margin of error for the 95% confidence interval used to estimate the population proportion.

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

8) n = 125, x = 72; 90% confidence

9) n = 195, x = 162; 95% confidence

Use the given data to find the minimum sample size required to estimate the population proportion.

10) Margin of error: 0.04; confidence level: 99%; from a prior study,

is estimated by 0.12.

11) Margin of error: 0.024; confidence level: 95%;

and

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unknown

Mean:

Do one of the following, as appropriate: (a) Find the critical value

, (b) find the critical value

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, (c) state that neither the normal nor the t distribution applies.

12) 91%; n = 45; σ is known; population appears to be very skewed.

13) 90%; n = 10; σ is unknown; population appears to be normally distributed.

Use the confidence level and sample data to find the margin of error E. Round your answer to the same number of decimal places as the sample mean unless otherwise noted.

14) The duration of telephone calls directed by a local telephone company:

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Round your answer to the nearest thousandth.

Assume that a sample is used to estimate a population mean μ. Use the given confidence level and sample data to find the margin of error. Assume that the sample is a simple random sample and the population has a normal distribution. Round your answer to one more decimal place than the sample standard deviation.

15) 99% confidence; n = 201;

= 276; s = 75

Use the given degree of confidence and sample data to construct a confidence interval for the population mean μ. Assume that the population has a normal distribution.

16) n = 30,

= 84.6, s = 10.5, 90% confidence

Use the given information to find the minimum sample size required to estimate an unknown population mean μ.

17) How many women must be randomly selected to estimate the mean weight of women in one age group. We want 90% confidence that the sample mean is within 3.4 lb of the population mean, and the population standard deviation is known to be 25 lb.

18) Margin of error: $135, confidence level: 95%, σ = $500