2021 · Q77
The average age of Raj and his father is 45 years. If the ages of the father and the grandfather of Raj are respectively two and three times that of Raj, then the age of Raj’s grandfather is
general-mental-abilityquantitative-aptitude
- A75 years
- B90 years
- C81 years
- D84 years
Explanation
Let Raj's age be R. His father's age is 2R and his grandfather's is 3R. The average of Raj's and his father's ages is 45, so (R + 2R)/2 = 45, giving 3R = 90 and R = 30. The grandfather's age is 3R = 90 years. Hence option B is correct.