You and your friend each start a car-washing service.
You spend $25 on supplies and charge $10 per car.
Your friend spends $55 on supplies and charges $13 per car.
How many cars do you have to wash to earn the same amount of money as your
friend?

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.