ASAP He pays $15 per month and $0.20 per minute for local air time. Calvin signed up for another plan. He pays $25 per month and $0.10 per minute.

a) Write an equation representing Korey's cellular phone service.

b) Write an equation representing Calvin's cellular phone service.

c) Solve a system of equations to calculate when Cory's and Calvin's costs are the same. After how many minutes will this occur? write your answer in the form (x, y)

An automobile assembly line operation has a scheduled mean completion time, μ, of 12 minutes. the standard deviation of completion times is 1.6 minutes. it is claimed that, under new management, the mean completion time has decreased. to test this claim, a random sample of 33 completion times under new management was taken. the sample had a mean of 11.2 minutes. assume that the population is normally distributed. can we support, at the 0.05 level of significance, the claim that the mean completion time has decreased under new management? assume that the standard deviation of completion times has not changed.