The Active Lifetime of Laptop Computers Is Normally Distributed, with a Mean

Short Answer

The active lifetime of laptop computers is normally distributed, with a mean of 36 months and a standard deviation of 6 months.
a. What is the probability that a randomly selected laptop will last less than 3.5 years?
b. What proportion of the laptops will last more than 32 months?
c. What proportion of the laptops will last between 2 and 4 years?