the times per workout an athlete uses a stair climber are normally distributed with a mean of 20 minutes and standard devation of 5 minutes what percebtage of athletes use the stair climber for less than 18 minutes

Which of the following are independent events? a) knowing that it is going to rain tomorrow, and bringing an umbrella to schoolb) knowing that you have to get up early tomorrow, and going to bed before 9 p.mc) knowing that it is going to rain tomorrow, and going to bed before 9 p.md) knowing that you have a test in school tomorrow, and studying thw night before