8. The cost of consumer purchases such as housing, gasoline, Internet services, tax preparation, and hospitalization were provided in The Wall Street Journal, January 2, 2007.

Sample data typical of the cost of tax-return preparation by services such as H&R Block are shown here.

120 230 110 115 160 130 150 105 195 155 105 360 120 120 140 100 115 180 235 255

a. Compute the mean, median, and mode.

b. Compute the first and third quartiles.

c. Compute and interpret the 90th percentile.