Which pair of measurements is not equivalent?

160 oz., 10 lb.
5 lb., 80 oz.
14,000 lb., 7 tons
4 tons, 6,000 lb.

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.