An advertising executive wants to estimate the mean weekly amount of time consumers spend watching traditional television daily. Based on previous? studies, the standard deviation is assumed to be 18 minutes. The executive wants to? estimate, with? 99% confidence, the mean weekly amount of time to within plus or minus ±5 minutes.
a. What sample size is? needed?
b. If? 95% confidence is? desired, how many consumers need to be? selected?