Question

A market research firm has been contracted to determine television viewing habits. The firm selected a random sample of 16 children during a week and obtained a mean of 24 hours and a standard deviation of 7 hours.

a) State what assumption you must make before you can construct a confidence interval.

b) Construct a 90% confidence interval for the mean number of hours children spend watching television. Include a statement.

c) The margin of error in part (a) was considered to be too large. What sample size is required to reduce the margin of error to 1.5 hours or less at a 90% confidence level? Assume the sample standard deviation of 7 hours is a good estimate of the population standard deviation.

Answer 1