7.51 8.22 7.86 8.36
8.09 7.83 8.30 8.01
7.73 8.25 7.96 8.53
Avending machine is designed to dispense 8 ounces of coffee into a cup. After a test that recorded the number ofounces of coffee in each of 1,000 cups dispensed by the vending machine, the 12listed amounts, in ounces, were selected from the data. If the 1,000 recorded amounts have a mean of8.1 ounces and a standard deviation of 0.3 ounce, how many of the 12 listedamounts are within 1.5 standard deviations of the mean?
Four
Six
Nine
Ten
Eleven
within 1.5 standard deviation的意思就是 小于standard deviation的值乘上1.5的字面意思