I need to know how to use the formula to answer these questions.
The time needed to drive from town A to town B is normally distributed with a mean of 180 minutes and standard deviation of 20 minutes. What is the probability that a person will drive from town A to town B in i) three hours or more, ii) in less than 180 minutes, iii) in more than 140 minutes, iv) in exactly three hours, and v) in less than 2.5 hours?