Question

The average age of 3girls is 17 years 4 months. The average age of 2 of them is 17years 3 months, how old is the third girl

Answer 1

Answer:

17 years 6 months

Step-by-step explanation:

Let the required age be 'x'

Now,  the average of the 3 girls' ages is 17 yrs 4 months = 208 months

         = x + (sum of ages of other girls) / 3 = 208 - (1)

Also, the average of the other girls' ages is 17 yrs 3 months = 207 months

       = (sum of ages of other girls) / 2 = 207

       => sum of ages of other girls = 414

Now back to first eqn. (1)

     = x +414 / 3 = 208    

     => x + 414 = 624

          x = 624-414 = 210 months = 17 yrs 6 months