3. The amount of time spent by American adults playing sports per week is normally

distributed with a mean of 4 hours and standard deviation of 1.25 hours.

a. Find the probability that a randomly selected American adult plays sports for more

than 5 hours per week.

(4

marks)

b. Find the probability that if four American adults are randomly selected, their average

number of hours spent playing sports is more than 5 hours per week. (6 marks)

c. Find the probability that if four American adults are randomly selected, all four play

sports for more than 5 hours per week.

(6 marks)