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.

I have a question see they have given average age of parents is 35 but they didn't which parents, so grandparents are parents of the existing two parents rite.

Therefore there are totally 4 parents and the total age of parents should be (35*4) not (35*2) and the answer is none of the above.

My answer is 40 2/7.

That's current value is not better for this question.

@Tamilazhagan

Yes you are correct that is the correct process and answer is none of these.

I think total members are 11. Because parent = mother and father. So 2 parents is equal for 2 mother and 2 father. Then grand parents are also 2 grand mother and 2 grand father. So total members are 11.

I wanted to know how it comes from 222/7 to 31 5/7?

How do you know they have 3 children. Confused?

Question says A family, so I think in a family there will be one grandpa and granny and also there will be only one mom and one dad. So answer is right.

In this problem mention two grandparents (i.e. two grandfather and two grand mother) then how it come total member in this family is 7?

I think total member is 11 explain me.

Now see, let denote grand parent by gp,

The average age of grandparents is given as 67,
Which means (gp1+gp2)/2 is equal to 67.

Similarly,
(p1+p2)/2 is equal to 35.

Similarly,
(gc1+gc2)/2 is equal to 6.

We are required to find,
(gp1+gp2+p1+p2+gc1+gc2)/7 is ?

So we found numerator by this way as:
67*2+35*2+6*2 = numerator.