B was born when A was 4 years 7 months old and C was born when B was 3 years 4 months old. When C was 5 years 2 months old, then their average age was:

8 years 11 months

A − B = 4years 7months ... (i)

B − C = 3years 4months... (ii)

By adding both the equations we get,

A − C = 7years 11months

Given : When,

C = 5 years 2 months

∴ A = 13 years 1 month

B = 8 years 6 months

Average = \(\frac{A + b + c}{3}\)

              = \(\frac{26 \; years\; 9 \;months}{3}\)

              = 8 years 11 months