Question

The average age of 80 girls was 20 years. If the average age of 20 of them was 22 years and that of another 20 was 24 years, find the average age of the remaining girls.

• A. 17 years
• B. 19 years
• C. 21 years
• D. 15 years
• E. None of these

Answer 1

The correct option is A 17 years

Total age of remaining 40 girls
$=(80\times 20-20\times 22-20\times 24)years=(1600-440-480)years=680years$
$\therefore$ Required average age
$=\frac{680}{40}=17years$