A research concludes that the number of hours of exercise per week for adults is normally distributed with a mean of 4 hours and a standard...

11. A research concludes that the number of hours of exercise per week for adults is normally distributed with a mean of 4 hours and a standard deviation of 2.5 hours. Show all work. Just the answer, without supporting work, will receive no credit.  

(a)  What is the probability that a randomly selected adult has at least 5 hours of exercise per week (round the answer to 4 decimal places)    (b) Find the 75th percentile for the distribution of exercise time per week. (round the answer to 2 decimal places)