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

Answer:

83

Step-by-step 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.

$\frac{71+80+86+x}{4}=80\\\frac{237+x}{4} =80\\237+x=320\\x=83$

The fourth test score must be an 83.

Answer 2

Answer:

83

Step-by-step 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