There have been a total of 380 astronauts selected by NASA since its first group, The Mercury Seven, in 1959. The average age of these individuals at the time of their selection follows a bell-shaped distribution with a mean of 33.86 years and a standard deviation of 3.24 years.

(a) Identify the mean and standard deviation using appropriate symbols.

(b) What percent of astronauts were between 24.14 y.o. and 37.10 y.o. at the time of their selection?

(c) What percent of astronauts were younger than 30.62 y.o. at the time of their selection?

(d) What age marks the cutoff for the oldest 0.15% of astronauts at the time of their selection?