Dave’s quiz scores are 60, 90, and 80. What is the score Dave would need on his next quiz to increase his overall averag

[Gmat_mission]

Dave’s quiz scores are 60, 90, and 80. What is the score Dave would need on his next quiz to increase his overall average score to 82?

A. 92
B. 94
C. 96
D. 98
E. 100

D

Source: Manhattan GMAT

[Brent@GMATPrepNow]

Dave’s quiz scores are 60, 90, and 80. What is the score Dave would need on his next quiz to increase his overall average score to 82?

A. 92
B. 94
C. 96
D. 98
E. 100

D

Source: Manhattan GMAT

After the next quiz, Dave will have taken 4 quizzes.
If the average of those 4 quizzes is 82, then it must be the case that: (sum of all 4 quizzes)/4 = 82
Multiply both sides of the equation by 4 to get: sum of all 4 quizzes = 328

If we let x = the required score on the fourth test, we can write: 60 + 90 + 80 + x = 328
Solve to get: x = 98

Answer: D