A stationer buys a gel pen Rs 20 and sells it at 20% profit. For what price should he buy it so that he can make 25% profit by selling for the same selling price. ​

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.