Question

Bill had 5 tests over the marking period. He knows he is receiving a 85 on his report card. He was looking back at his test and only has four grades: 80, 90, 100, 85. What was the score of the missing test? Please no silly answers or links ill report you.

Answer 1

70

Explanation:

(Not the most streamlined way but.)

Knowing that if he had 5 tests, and a mark of 85, we can determine the total average grade Bill received. 85*5=425

Then subtract the known grades

425-(90+85+100+80)=x

425-(355)=x

70=x

Bill would have scored 70 on that 5th test