Question

1.Construct the indicated confidence interval for the population mean u using a t-distribution

c=0.98 x=110 s=10 n=27

2. In a random sample of25people, the mean commute time to work was32.9minutes and the standard deviation was7.1

minutes. Assume the population is normally distributed and use a t-distribution to construct a98% confidence interval for the population mean u

.What is the margin of error of u? Interpret the results.

The confidence interval for the population mean u is _,_

3.In a survey of3425adults,1435say they have started paying bills online in the last year.

Construct a 99% confidence interval for the population proportion. Interpret the results.

A 99% confidence interval for the population proportion is _,_

4.In a survey of6000women,3431say they change their nail polish once a week. Construct a99 %

confidence interval for the population proportion of women who change their nail polish once a week.

A 99% confidence interval for the population proportion is _,_

5.A researcher wishes to estimate, with99% confidence, the population proportion of adults who are confident with their country's banking system. His estimate must be accurate within4% of the population proportion.

(a) No preliminary estimate is available. Find the minimum sample size needed.

(b) Find the minimum sample size needed, using a prior study that found that26% of the respondents said they are confident with their country's banking system.

(c) Compare the results from parts (a) and (b).

6.A researcher wishes to estimate, with95% confidence, the population proportion of adults who say chocolate is their favorite ice cream flavor. Her estimate must be accurate within3% of the population proportion.

(a) No preliminary estimate is available. Find the minimum sample size needed.

(b) Find the minimum sample size needed, using a prior study that found that26% of the respondents said their favorite flavor of ice cream is chocolate.

(c) Compare the results from parts (a) and (b).