:9. Solution. The observed average is 19, the expected average
20. The box SD is estimated by the sample SD, which is 4.  The SE
of the sum of the draws is 4 x 10 = 40.  The SE of the average of
the draws, that is, of the sample average, is 40/100 = .4. Then <p>

z = (19 - 20)/.4  =  1/.4 = -2.5 .  <p>

The area under the normal curve to the left of -2.5 is seen to be
.62%.  The correct choice is .6%. <p>