Hello, I am having trouble with this question and I could really use some help!

Suppose the life of a particular brand of calculator battery is approximately normally distributed with a mean of 85 hours and a standard deviation of 9 hours. Complete parts a through c. a. What is the probability that a single battery randomly selected from the population will have a life between 80 and 90 hours? P(80 x=90) = (Round to four decimal places as needed.)