The equation tan-1(8.5/7.7) = x can be used to find the measure of angle lkj

Can someone check if i did this right since i really want to make sure it’s correct. if you do you so much

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.

David is standing on the sixth rung of a ladder while painting his house. which expressions represent a change in david’s position of 2 rungs on the ladder? choose exactly two answers that are correct. a. 6+2 b. 6-2 c. 2x6 d. 6/2