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.

The table below shows the approximate masses of a dust particle and a grain of pollen. dust particle 0.000000778 g grain of pollen 0.00000000155 g the mass of a dust particle can be estimated and written in the form a × 10^b, where a = 8 and b = the mass of a grain of pollen can be estimated and written in the form a × 10^b, where a = 2 and b = based on the estimates, the mass of a dust particle is approximately blank times larger than the mass of a grain of pollen.