Suppose x = 7 is a solution to the equation 4x − 2(x + a) = 8. Find the value of a that makes the equation true. A: 2 B: 3 C: -25 D: 6

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.