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The average age of 10 children is 9 years 9 months. The average age of 9 children is 8 years 11 months. What is the age of the tenth child ?
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- 17 years 3 months
- 18 years 4 months
- 17 years 5 months
- 18 years 3 month
- 17 years 3 months
Correct Option: A
Given that , The average age of 10 children = 9 years 9 months
Total age of 10 children = ( 9 years 9 months ) × 10
The average age of 9 children = 8 years 11 months
Total age of 9 children = ( 8 years 11 months ) × 9
∴ Age of tenth child = (9 years 9 months) × 10 – (8 years 11 months) × 9
Age of tenth child = 97 years 6 months – 80 years 3 months = 17 years 3 months
