The Life Expectancy of Computer Terminals Is Normally Distributed with a Mean

The life expectancy of computer terminals is normally distributed with a mean of 4 years and a standard deviation of 10 months.
a.What is the probability that a randomly selected terminal will last more than 5 years?
b.What percentage of terminals will last between 5 and 6 years?
c.What percentage of terminals will last less than 4 years?
d.What percentage of terminals will last between 2.5 and 4.5 years?
e.If the manufacturer guarantees the terminals for 3 years (and will replace them if they malfunction), what percentage of terminals will be replaced?