3.66. According to a report from the U.S. National Cen- ter for Health Statistics, for males age 25-34 years, 2% of their heights are 64 inches or less, 8% are 66 inches or less, 27% are 68 inches or less, 39% are 69 inches or less, 54% are 70 inches or less, 68% are 71 inches or less, 80% are 72 inches or less, 93% are 74 inches or less, and 98% are 76 inches or less. These are called cumulative percentages.

(a) Find the median male height.

(b) Nearly all the heights fall between 60 and 80 inches, with fewer than 1% falling outside that range. If the heights are approximately bell shaped, give a rough approximation for the standard deviation. Explain your reasoning.