Question

5 years ago the average age of a,b,c,and d was 45.with e joining the average age of all the five is 46 years .how old e?

Answer 1

5 years ago the average age of a,b,c,and d was 45. i.e.,

a+b+c+d/4=45

a+b+c+d+=180-------->1

with e joining the average age of all the five is 46 years i.e.,

a+b+c+d+e/5=46

a+b+c+d+e=230---------->2

from we get 180+e=230

e=50 years before 5 years    .     e's present age is 55 years

Answer 2

let the sum of ages of a,b,c and d = x

average = x/no. of people =45

              ⇒ x/4=45

             ⇒x=45 × 4

              x = 180

Now let the sum of the ages of a,b,c,d and e = y

average = y/5 =46

            ⇒y = 46 × 5

               y = 230

x = a + b + c + d = 180

y = a + b + c  + d +e =230

so the age of e = (a + b +c + d + e) - (a + b + c  + d)

                        ⇒ y - x

                        =230 - 180

                       = 50

so the age of e is 50 years