Suppose scores on exams in statistics are normally distributed with an unknown population mean and population standard deviation of three points.A random sample of 49 scores are taken and gives a sample mean of 78.Find a 93% confidence interval for the population mean of the stats exam scores.

Suppose you do a study of acupuncture to determine how effective it is in relieving pain.You measure sensory rates for 15 subjects with the results given.Construct a 90% confidence interval for the mean sensory rate for the population (assumed normal) from which you took the data.

8.6

9.4

7.9

6.8

8.3

7.3

9.2

9.6

8.7

11.4

10.3

5.4

8.1

5.5

6.9

Suppose that a market research firm is hired to estimate the percent of adults living in a large city who have cell phones.Four hundred randomly selected adult residents in this city are surveyed to determine whether they have cell phones.Of the 400 people surveyed, 331 responded yes - they own cell phones.Using a 92% confidence level, compute a confidence interval estimate for the true proportion of adult residence of this city who have cell phones.