:9. A box contains numbered tickets. The box average is
supposed to be 20. 100 tickets are drawn from the box (with
replacement). The average value of the numbers on these tickets
turns out to be 19, and the standard deviation turns out to be 4.
Let the null hypothesis be that the box average is 20, and let
the alternate hypothesis be that the box average is less than 20.
Using
z = (observed average - expected average)/SE(of average),

the P-value of the test is seen to be closest to

a. .6%
b. 1.2%
c. 12%
d. 68%
e. 95%