NU wants to estimate the mean time spent by its students commuting daily to campus. The population standard deviation time spend commuting is 8 minutes. A random sample of 49 students reveals a mean of 20.5 minutes.
a. Construct a 99 percent confidence interval estimate for the population mean time spent by NU students commuting daily to campus?
b. Within 99 percent confidence, what sample size is needed if NU wants to be within (+/-) 1 minute of the true population parameter?
Please explain and show work (including graphs if necessary).