Bradley washed 8 cars. He earned $10, $12,

$15, $15, $15, $9 and $10 for 7 cars. How

much did he earn the eight time if the mean

of the data is $12?

Add the amounts for the first 7 cars:

10 + 12 + 15 + 15 + 15 + 9 + 10 = $86

The mean is the average, if the mean is $12, multiply that by the total cars (8):

12 x 8 = $96

This means for 8 cars he earned $96.

To find the amount he made for the 8th car, subtract the total he earned from the 7 cars from the total he made for all 8:

96 - 86 = 10

He earned $10 for the 8th car.