840/1152 simplified please

Tracy solved the following problem. which of the statements is true? 9 ÷ 3 + 6 × 2 3 + 6 × 2 9 × 2 18 her answer is correct. her answer is incorrect. she should have multiplied before dividing. her answer is incorrect. she should have multiplied before adding. her answer is incorrect. she should have added before dividing.

Which statement accurately explains whether a reflection over the y-axis and a 270° counterclockwise rotation would map figure acb onto itself? a coordinate plane with figure acb with point a at 1, 1, c at 3, 4 and b at 5, 1 yes, a″c″b″ is located at a″(1, 1), c″(4, 3), and b″(1, 5) yes, a″c″b′ is located at a″(1, 1), c″(3, 4), and b″(5, 1) no, a″c″b″ is located at a″(1, 1), c″(4, 3), and b″(1, 5) no, a″c″b″ is located at a″(1, 1), c″(3, 4), and b″(5, 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.