The costs of general admission and student tickets to a high school football game are $7 and $4 respectively. The ticket sales for one game totaled $11,200. Write an equation which models the situation.

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.