Question

Skylar's grades on four math tests are 85, 78, 77, and 69. What does Skylar need to score on the next test in order to have a mean score of 80?

Answer 1

• 91

Explanation:

The mean the the average of 5 numbers. If the next score is x, then the mean is:

• (85 + 78 + 77 + 69 + x)/5 = 80

Solve it for x:

• 309 + x = 80*5
• x = 400 - 309
• x = 91

Answer 2

It is given that,

The mean is the average of 5 numbers.

Then if the,

Next score is x the mean will be.

We can solve now,

→ (85 +78 +77 + 69 + x)/5 = 80

→ (309 + x)/5 = 80

→ 309 + x = 80 × 5

→ 309 + x = 400

→ x = 400 - 309

→ x = 91

Hence, the next score is 91.