-
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.
-
- 40%
- 50%
- 55%
- 60%
Correct Option: A
Let the number of boys be x and that of girls be y.
Then, 71x + 73y = 71.8 (x + y)
⇒ 71.8x – 71x = 73y – 71.8y
⇒ 0.8x = 1.2y
| ⇒ | = | = | = | |||||
| y | 0.8 | 8 | 2 |
| ⇒ | + 1 = | + 1 ⇒ | = | |||||
| y | 2 | y | 2 |
∴ Percentage of girls
| = | × 100 = | × 100 = 40% | ||
| x + y | 5 |
