A random variable is normally distributed with a mean of? = 50 and a standard deviation of? = 5

A random variable is normally distributed with a mean of? = 50 and a standard deviation of? = 5.

a. What is the probability the random variable will assume a value between 45 and 55 (to 4 decimals)?

b. What is the probability the random variable will assume a value between 40 and 60 (to 4 decimals)?