Aptitude - Average - Discussion

Your calculation wrong @Mr.Siva.

Because the given question is 2 grandparents, 2 parents, 3 grandchildren.

Average age of grandparents is 67. So age of two grandparents is 67*2 = 134. Average age of parents is 35. So age of two parents is 35*2 = 70. Average age of three grandchildren is 6. So age of three grandchildren is 6*3 = 18.

Average = Sum of observation/Number of observation.

Average = 134+70+18/2+2+3.

Average = 222/7.

We convert ordinary fraction into mixed fraction.

So finally we get average = 31 5/7.

Average = Sum of total ages/No of person.

Average = 67*2+35*2+6*3/2+2+3.

= 134+70+18/7 = 222/7 = 31 5/7.

Can you explain 31 5/7 with formula ?

@Shubham Sanware.

It is the mixed fraction of 222/7. When you divide 222 with 7 we get 31 as quotient and remainder 5.

Mixed fraction = quotient remainder/divisor.

So, its 31 5/7.

@Tamilazhagan.

Parent means either mummy or daddy.

Parents means couple so we (67*2+35*2+6*3)/2+2+3 = 222/7 = 31 5/7.

How the 5 is coming? Can anyone explain what is remainder?

Required average = 67 x 2 + 35 x 2 + 6 x 3.
-----------------------
2 + 2 + 3
= 134 + 70 + 18
---------------
7
= 222
-----
7
= 31 5 years.
-
7

Divide:

7)222(31
- 21
-------
12
- 7
-------
5
-------
so that is right it like 31 5
--------------------------
7

How comes 5/7 I got 31.7142?

Please explain, why for parents also your multiplying by 2 and for two grandparents also multiplying by 2. Why can't we consider like this.

For parents means = Father and mother, hence its multiplied by 2.

For 2 grandparents means = Father's father, father's mother, mother'father, mothers mother, hence it should be 4.

Please some one reply am I right or wrong, if no please explain.

Can someone crack such problems with some other approach, shortcut maybe?