Question

Laura mowed 8 lawns. She earned $12, $10, $15, $15, $15, $10, and $9 for seven lawns. How much did she earn the eighth time if the mean of the data is $12? *

Answer 1

She earned $10 for the eighth yard.

Explanation:

You have 7 known numbers and 1 unknown giving you a total of 8 numbers. When doing mean, you add up all the numbers and divide by the amount of numbers you have (in this case 8). If you add all the numbers in this particular data set you get 86. You know that you have to divide by 8 and you need 12 to be the answer. Using multiplication facts, we know that 96 divided by 8 is equal to 12. That means the answer must be 10 for the eighth yard because 86+10=96.

Answer 2

She earned $10 for mowing the 8th lawn.

Explanation:

Let's use the average formula and n = 8, with x representing the 8th score:

12 + 10 + 15 + 15 + 15 + 10 + 9 + x

average = 12 = -------------------------------------------------

8

86 + x

Summing up the numerator, we get average = ----------- = 12

8

Multiplying both sides by 8 yields 86 + x = 96

Solving for x, we get x = 10.

She earned $10 for mowing the 8th lawn.