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The average score of a-class of boys and girls in an examination is A. The ratio of boys and girls in the class is 3 : 1. If the average score of the boys is A + 1, the average score of the girls is
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- A + 1
- A – 1
- A + 3
- A – 3
- A + 1
Correct Option: D
Let the number of boys in the class be 3k. The ratio of boys and girls in the class is 3 : 1, then the number of girls in the class is k.
| ∴ Average score of the girls = | (3k + k) × A - 3k(A + 1) |
| k |
| Average score of the girls = | 4kA - 3kA -3k |
| k |
| Average score of the girls = | kA - 3k | = | k(A - 3) | = A - 3 |
| k | k |
