a shoe store that sells only boots and sandals had 20% more pairs of boots than sandals in its inventory . After receiving a shipment of 20 more pairs of sandals, the store had a total of 306 pairs of shoes. How many pairs of boots did the store have?

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.