Two airplanes leave the airport at the same time, flying in opposite directions. One plane flies 100 miles per hour faster than the other. They fly for 4 hours and end up 2,000 miles apart. How fast do they each fly?

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.