It has been reported that American taxpayers spend 6.6 billion hours filling out tax forms each year. You take a random sample of 1500 taxpayers and find the average time filling out tax forms for the sample is 28.4 hours, with a sample standard deviation of 5.7 hours.
a. Use sample results to build a 95% confidence interval estimate of the average time taken filling out tax forms for the population of all American taxpayers.
b. If there are 150 million taxpayers in the US, show the 95% confidence interval for the total hours taken filling out tax forms for this population.