Alex was thinking of a number. Alex doubles it, then adds 20 to get an answer of 22. 7. What was the original number?.

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.