A certain type of storage battery lasts, on average 3.0

A certain type of storage battery lasts, on average 3.0 years with a standard deviation of 0.5 year. Assuming that battery life is normally distributed, answer the following question.

a. What is the probability that a randomly selected above types of battery will last more than 2.3 years?
b. What is the probability that a randomly selected above types of battery will last more between 2 to 2.3 years?

c. What is the 90th percentile of the above distribution of the lifetime of the battery? Interpret 90th percentile related to this question.