Please help me on this

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.

Xy x xy if a and b are positive integers such that a*b=9 and b*a=72 what is the value of a/b

Ineed to know how to write question one in mathematical terms