csateasy
A student on her first 3 tests received an average score of N points. If she exceeds her previous average score by 20 points on her fourth test, then what is the average score for the first 4 tests?
- A.N + 20
- B.N + 10
- C.N + 4
- D.N + 5
▶ Answer & Explanation
Correct answer: D. N + 5
The total score for the first three tests is 3N. The score on the fourth test is N + 20. Therefore, the total score for the four tests is 3N + (N + 20) = 4N + 20. The average score for the four tests is (4N + 20) / 4, which simplifies to N + 5.
Source: UPSC csat 2011