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In a class, the average score of girls in an examination is 73 and that of boys is 71. The average score for the whole class is 71.8. Find the percentage of girls.
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- 40%
- 50%
- 55%
- 60%
- 40%
Correct Option: A
Let the number of boys be p and that of girls be q.
∴ 71p + 73q = 71.8 (p + q)
⇒ 71.8p – 71p = 73q – 71.8q
⇒ 0.8p = 1.2q
| ⇒ | = | = | = | ||||
| q | 0.8 | 8 | 2 |
| ⇒ | + 1 = | + 1 ⇒ | = | ||||
| q | 2 | q | 2 |
| ∴ Percentage of girls = | × 100 = | × 100 = 40% | ||
| p + q | 5 |
