Question

Scores are 78,81,83, and 76 what must she earn on the fifth test to earn an average test score of 81

Answer 1

The average value of a data set is equal to the sum of each entry divided by the number of entries. In this case, we have 5 scores, so we can find set up the following equation where x is the fifth score:

$\dfrac{78+81+83+76+x}{5} = 81$

Now solve for x:

$78 + 81 + 83 + 76 + x = 81(5)$

$318 + x = 405$

$x = 87$

The fifth score must be 87.

Answer 2

87%.
Because:
 1) 78+81+83+76+87=405
2) 405/5=81
You add up all the test scores and then divide by 5 because thats how many test there are.