The average age of a class of 65 boys was 14 years, the average age of 20 of them was 14 years, and that of another 15 was 12 years. Find the average age of the remaining boys.
A. 16 years
B. 13 years
C. 17 years
D. 15 years
Answer: Option D
Solution (By Examveda Team)
Total age of 65 boys=(65*14)=910 yrs.Total age of 20 boys=(20*14)=280 yrs.
Total age of 15 boys=(15*12)=180 yrs.
Therefore, avg. age of rem. 30 boys=[{910-(280+180)}]/30=15 yrs.
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Total age of 65 boys=(65*14)=910 yrs.
Total age of 20 boys=(20*14)=280 yrs.
Total age of 15 boys=(15*12)=180 yrs.
Therefore, avg. age of rem. 30 boys=[{910-(280+180)}]/30=15 yrs.
Answer = Option ( D )
Required average
= ( 65*14 ) - ( 20*14+15*12 ) / 65 - ( 20+15 )
= ( 910 - 460 ) /30
= 450/30
= 15