The average age of A and B is 20 years. If A is to be replaced by C, the average would be 19 years. The average age of C and A is 21 years. The ages of A, B and C in order (in years) are:
Answer & explanation
Correct answer: option 3
average age of A and B is 20 years
A + B = 40 years ----- ( 1)
The average age of C and A is 21 years
C + A = 42 years ------ ( 2)
if A is replaced by C . then , average of B and C is 19 years.
B + C = 38 years ------ ( 3 )
adding equation, 1 + 2 + 3
A+ B + C = 60 years
( A + B + C ) - ( A + B ) = 60 - 40
C= 20 years
( A + B + C ) - ( B + C ) = 60 - 38
A = 22 years
( A + B + C ) - ( A + C ) = 60 - 42
B = 18 years
so the age of A , B and C is 22 , 18 , 20 years respectively .