5. Ms. Lee bought 8 tickets to the basketball game and spent a total of $30. She bought a combination of adult tickets for $5 and child tickets $3 each. Which system of equations below will determine the number of child tickets, c, and the number of adult tickets, a, she bought?​

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.