You randomly choose a marble from a bag of 7 green marbles and 4 blue marbles. You replace the marble and draw another.
You choose a green marble, then you choose a blue marble.
What is the probability that you choose a green marble?
What is the probability that you choose a blue marble?
What is the probability that you choose a green marble AND then a blue marble?

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.