When 2 people play tennis it is called singles. when 4 people play it is called doubles. in doubles it is 2 players playing against two players below is a diagram of a tennis court the net divides the court in half the two alleys on the side are used only in doubles what is the total length of a tennis court

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.