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Games, Puzzles and Quizzes

Blazing goIITian

Joined:	25 Jul 2011
Post:	322

4 Dec 2011 17:38:01 IST

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323

Brainteaser

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Mary, who is sixteen years old, is four times as old as her brother. How old will Mary be when she is twice as old as her brother?

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hemang

Blazing goIITian

Joined: 27 Dec 2010

Posts: 1474

6 Dec 2011 11:45:49 IST

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let the present age of her brother be x.

then her present age is 4x.

also given that 4x = 16.

so x = 4.

present age of her brother is 4.

the difference between their ages is 12 and it remains constant...

the age after y years of her brother will be 4+y.

then her age will be 16+y.

16+y = 2(4+y) = 8 + 2y.

so we have y = 8 years.

after 8 years her age will be 24.

her brother's age will be 4 + 8 = 12 years..

Rahul Sasi K

New kid on the Block

Joined: 26 Aug 2011

Posts: 3

6 Dec 2011 13:11:01 IST

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We have , age of Mary = 16hence her brothers age = 4now difference in their age = 12When Mary is aged double her brother( be x age ) would be 2x . But the difference in their age stays .therefore ,2x - x = 12so x = 12Brothers age = 12marys age =24

Rahul Sasi K

New kid on the Block

Joined: 26 Aug 2011

Posts: 3

6 Dec 2011 13:13:18 IST

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Sorry , the answer wasnt punctuated .

We have ,

present age of Mary = 16

hence her brothers age = 4

now difference in their age = 12

When Mary is aged double her brother( be x age ) would be 2x . But the difference in their age stays

.therefore ,

2x - x = 12

so x = 12

Brothers age = 12

marys age =24

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