Ted needs an average of at least 70 on his three history tests. He has already scored 85 and 60 on two tests. What is the mimimum grade ted needs on his thirds test

Answer 1

x = result of the third test

After the third test, his average will be:

( 85 + 60 + x ) / 3

Ted needs an average of at least 70 on his three history tests means:

( 85 + 60 + x ) / 3 ≥ 70

( 145 + x ) / 3 ≥ 70

Multiply both sides by 3

145 + x ≥ 210

Subtract 145 to both sides

x ≥ 65