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In a school, the average age of students is 6 years, and the average age of 12 teachers is 40 years. If the average age of the combined group of all the teachers and students is 7 years, then the number of students is :
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- 396
- 400
- 408
- 416
- 396
Correct Option: A
Let the number of students be n. Then,
According to question ,
| 7 = | n × 6 + 12 × 40 |
| n + 12 |
⇒ 7n + 84 = 6n + 480
⇒ n = 480 – 84 = 396
