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The average age of 24 boys and their teacher is 15 years. When the teacher’s age is excluded, the average age decreases by 1 year. The age of the teacher is
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- 38 years
- 39 years
- 40 years
- 41 years
- 38 years
Correct Option: B
Given that , The average age of 24 boys and their teacher = 15 years.
Total age of 24 boys and teacher = (24 + 1) × 15
When the teacher’s age is excluded, Total decrease age = 24 × (15 – 1)
The age of the teacher = (24 + 1) × 15 – 24 × (15 – 1)
∴ The age of the teacher = 25 × 15 – 24 × 14 = 375 – 336 = 39 years.
