In a family of 21 people, the average age is 14years. If the age of the grandfather is not counted, the average age drops to 12 years. What is the age of the grandfather?
35 years
40 years
42 years
54 years
Explanation
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Discussions (10)
Total age of the whole family = 21 x 14 = 294
Total age without the grandfather = 20 x 12 =
240
Age of grandfather = 294 - 240
= 54 years
The answer should be 54
21×14=294
without the grandpa then.
21-1=20
So the average age without the grandpa is
20×12=240
The grandpa's age will be
294-240=54
The selected answer is wrong:
The total age of the whole family is=the number of people in the family multiplied by the mean age i.e 21 X 14=294 and on the other hand.Given that the mean age of the family dropped to 12 due to the removal of the age of the grandfather,we have 21 minus the grandfather,we are left with 20 individuals,so 20 x 12=240.....the age of the grandfather will now be 294 - 240=54;THE AGE OF THE GRANDFATHER THEREFORE IS 54
how can you divide the 2nd statement with 21 when the grandfather was not counted?....it nshould be (21-1)
when calculating the grandfather is supposed to be removed from the total, meaning that the total equals 20
