Question: A student scores 80, 90, and 70 in three subjects. If he wants to achieve an average of 85 after scoring in a fourth subject, what score does he need?

Options:

1. 90
2. 95
3. 100
4. 85

Correct Answer: 95

Solution:

The current total score is 80 + 90 + 70 = 240. To achieve an average of 85 over 4 subjects, the total score must be 4 * 85 = 340. Therefore, the score needed in the fourth subject is 340 - 240 = 100.