Question

2. The American Council of Life Insurers provides information about life insurance in force per covered family in the Life Insurers Fact Book. Assume that the standard deviation of life insurance in force is $50,900.

a. Determine the probability that the sampling error made in estimating the population mean life insurance in force by that of a sample of 500 covered families will be $2000 or less

b. Must you assume that life-insurance amounts are normally distributed in order to answer part (a)? What if the sample size is 20 instead of 500?

3. A city planner working on bikeways designs a questionnaire to obtain information about local bicycle commuters. One of the questions asks how long it takes the rider to pedal from home to his or her destination. A sample of local bicycle commuters yields the following times, in minutes.

22	19	24	31	29	29	23	48
21	15	27	23	37	31	22	29
30	26	16	26	12	28

a. Graphical analyses of the data indicate that the data are roughly normally distributed but the time of 48 minutes may be an outlier. Remove this outlier and test at the 5% significance level, do the data provide sufficient evidence to show that the mean commuting time of all local biker less than the value of the outlier of 48 minutes. (Note: Remove the outlier before working on the test.)

b. Find a 90% confidence interval for the mean commuting time of all local bicycle commuters in the city. (Note: Remove the outlier first.)

Answer 1

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