Max is stacking logs at his campground for firewood. after his first load of logs, he has 9 logs on the stack. after his seventh load of logs, he has 51 logs on the stack. use sequence notation to represent the arithmetic function.
a an = 51 + 6(n − 1)
b an = 9 + 6(n − 1)
c an = 51 + 7(n − 1)
d an = 9 + 7(n− 1)

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.