Subject: General Aptitude · Chapter: Average · Exam: 2006 · Marks: · Difficulty:
The average age of A and B is 20 years. If A is replaced by C, the average age becomes 19 years and if B is replaced by C, the average age becomes 21 years. Find the ages of A, B and C.
Answer
Answer (as printed):
Explanation
Clearly, average age of A and B = 20 years; average age of B and C = 19 years; average age of A and C = 21 years. Sum of ages of A and B = (20 × 2) years = 40 years ...(i) Sum of ages of B and C = (19 × 2) years = 38 years ...(ii) Sum of ages of A and C = (21 × 2) years = 42 years ...(iii) Adding (i), (ii) and (iii), we get: 2 (Sum of ages of A, B and C) = 120 years ⇒ (Sum of ages of A, B and C) = 60 years ...(iv) Subtracting (i) from (iv), we get: C’s age = (60 – 40) yrs = 20 years Subtracting (ii) from (iv), we get: A’s age = (60 – 38) yrs = 22 years Subtracting (iii) from (iv), we get: B’s age = (60 – 42) yrs = 18 years
Explanation as extracted from the printed page; notation may be imperfect.