The average age of 3 girls is 24 years and their ages are in the proportion of 7 : 8 : 9. What is the age of the eldest girl?

24 years 25 years 21 years 27 years

27 years

Sum of ages of 3 girls = 3 × 24 = 72 years Ratio of their ages = 7 : 8 : 9 ATQ, 24R = 72 years 1R = 3 years Ages of Eldest girl = 9 × 3 = 27 years