Jim has grades of 84, 65, and 76 on three math tests. What grade must he obtain on the next test to have an average of exactly 80 for the four tests?. A. 87 . B. 95 . C. 85 . D. 92
An average for the four tests: Avg = ( 84 + 65 + 76 + x ) / 4 80 = ( 84 + 65 + 76 + x ) / 4 /* 4 ( multiple both sides of the equation by 4 ) 320 = 225 + x x = 320 - 225 x = 95 Answer: B ) 95
