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The average age of the boys in a class is 18 years. The average age of the girls in that class is 12 years. If the ratio of the number of boys and girls in that class is 3 : 2, then the average age of the class is :
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- 15. 6 years
- 16. 5 years
- 15 years
- 16 years
- 15. 6 years
Correct Option: A
Let the number of boys in the class be 3k and that of girls be 2k.
| ∴ Average age of class = | 3k × 18 + 2k × 12 |
| 3k + 2k |
| Average age of class = | 54k + 24k |
| 5k |
| Average age of class = | 78 |
| 5k |
Average age of class = 15.6 years
