It rained 2/8 inch in one hour. if rained 4/8 inch in the next hour. find the total amount of rain. wrote in simplest form

Monitors manufactured by tsi electronics have life spans that have a normal distribution with a standard deviation of 1800 hours and a mean life span of 20,000 hours. if a monitor is selected at random, find the probability that the life span of the monitor will be more than 17,659 hours. round your answer to four decimal places.