Four years ago, the Father's age was three times

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Four years ago, the Father's age was three times the age of his son. The total of the ages of the father and the son after four years, will be 64 years. What is the father's age at present ?

(A). 32
(B). 36
(C). 44
(D). 12
(E). Data inadequate.

Answer is B

Please help on this one. It looks easy to me, but i am not able to get the answer.

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Vinni
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by aditya8062 » Tue Apr 02, 2013 12:22 am
my take wud be that fathers present age is 40
and son is 16 .logic is simple u can check these figures with the conditions given in the question

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by hemant_rajput » Tue Apr 02, 2013 2:35 am
vinni.k wrote:Four years ago, the Father's age was three times the age of his son. The total of the ages of the father and the son after four years, will be 64 years. What is the father's age at present ?

(A). 32
(B). 36
(C). 44
(D). 12
(E). Data inadequate.

Answer is B

Please help on this one. It looks easy to me, but i am not able to get the answer.

Thanks & Regards
Vinni
Father's present age = F
Son's present age = S

4 year ago

F - 4 = 3(S -4)
F - 4 = 3S - 12

F + 8 = 3S ------ equation 1

after 4 year

F + 4 + S + 4 = 64
F + S = 56 ------- equation 2

we have 2 equations and 2 unknown
Multiplying equation 2 by 3 and adding two equation
F - 3S = (-8)
3F + 3S = 168
---------------
4F = 160

F = 40.
hence, S = 16


One more thing the option pattern given in this question doesn't comply with gmat's pattern. You'll always have some know value or range in the options, so that you can directly plugin the numbers and check for the answer which this question doesn't provide. So if you are preparing for GMAT only stop doing questions from incompatible sources because they can throw off your study in different direction and that can be really harmful.


hope this helps,

kudos,
Hemant
I'm no expert, just trying to work on my skills. If I've made any mistakes please bear with me.

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by GMATGuruNY » Tue Apr 02, 2013 2:44 am
vinni.k wrote:Four years ago, the Father's age was three times the age of his son. The total of the ages of the father and the son after four years, will be 64 years. What is the father's age at present?

(A). 32
(B). 36
(C). 44
(D). 12
(E). Data inadequate.

Answer is B
The answer choices seem to represent the father's age FOUR YEARS AGO.

Since four years ago the father was 3 times as old as his son was then, the father's age four years ago must be a multiple of 3.
Eliminate A and C.
Since four years from now the sum of the father's age and the son's age must be 64, answer choice D (12) is too small.
Eliminate D.

Thus, the father age four years ago must be 36, implying the following:
Since four years ago the father was 3 times as old as his son was then, the son's age four years ago = 36/3 = 12.
Father's current age = 36+4 = 40.
Son's current age = 12+4 = 16.
Father's age four years from now = 40+4 = 44.
Son's age four years from now = 16+4 = 20.
Sum of the ages four years from now = 44+20 = 64.
Success!

Thus, the father's current age = 40, and his age four years ago = 36.

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by vinni.k » Tue Apr 02, 2013 10:23 am
Thank you very much for your replies, and i completely agree with the answer (F=40). This is the exact answer that i was getting. Now i believe i have wrong explanation for this question.


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Vinni