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A student scored 75%, 80% and 85% in three subjects. If the marks of a fourth subject are also included, then his average percentage cannot be less than:

1. 60%
2. 65%
3. 80%
4. 90%

Correct answer: 60%

Solution

The lowest the fourth mark can be is 0%, giving average (75+80+85+0)/4 = 60%, so the average cannot fall below 60%.

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