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The average age of 30 girls is 13 yr. The average of first 18 girls is 15 yr. Find out the average age of remaining 12 girls.
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- 12yr
- 10yr
- 16yr
- 10.5 yr.
- None of the above
Correct Option: B
Total age of 30 girls = 30 x 13 = 390 yr
Total age of 18 girls = 18 x 15 = 270 yr.
∴ Age of remaining 12 girls = 390 - 270 = 120 yr
∴ Required average = 120/12 = 10 yr
