The amounts of time per workout an athlete uses a stairclimber are normally​ distributed, with a mean of 25 minutes and a standard deviation of 5 minutes. Find the probability that a randomly selected athlete uses a stairclimber for​ (a) less than 21 ​minutes, (b) between 25 and 34 ​minutes, and​ (c) more than 40 minutes. ​(a) The probability that a randomly selected athlete uses a stairclimber for less than 21 minutes is nothing.