Question

Terry scored 71, 80, and 86 on his first three history tests. What must terry score on the fourth test to have a mean of exactly 80

Answer 1

83

Explanation:

You are trying to find the score that gives you a specific mean. A mean is calculated by dividing the sum of the data by the amount of data. Set up in this order, with x as the fourth score, to find the answer.

`(71+80+86+x)/(4)=80\\(237+x)/(4) =80\\237+x=320\\x=83`

The fourth test score must be an 83.

Answer 2

83

Explanation:

Equation: 71 + 80 + 86 + x / 4 = 80

Add 71, 80, and 86 together.

237 + x = 80

Multiply 4 to both sides (cross multiplying).

237 + x = 320

Subtract 237 from both sides.

x = 83