The US National Center for Education Statistics surveys colleges and universities to obtain data on the cost of attending college. A random sample of 150 four-year colleges shows a mean of $16,107 for tuition and fees. (round to the 2nd decimal place)
a) Knowing that s = $4,241, obtain a 95 % confidence interval for the mean tuition and fees for all four year colleges.
b) Obtain a 90% confidence interval for the mean tuition and fees for all four year colleges.
c) Interpret your answer in part (a)
d) How does decreasing the confidence level affect the margin of error?