At the start of March, the value of an investment was $70.00 each month for 4 months this investment lost $15.What is the value of the investment after the 4 months

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.