A local police department attempted to estimate the average rate of speed (X) of vehicles along a strip of Main Street. With hidden radar, the speed of a random selection of 25 vehicles was measured, which yielded a sample mean of 42 mph and a standard deviation of 6 mph.
a. Estimate the standard error of the mean.
b. Find the 95% confidence interval for the population mean.
c. Find the 99% confidence interval for the population mean.