Math Is Fun Forum

Prakash Panneer

Member

Registered: 2006-06-01

Posts: 110

Algebra.

Father is aged three times more than his son Rohit. After 8 years, he would be 2 and half times of Rohit's age. After further 8 years how many times would be Rohit's age.

I have a doubt in the first statement.

F = 3 R. Is this right?

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John E. Franklin

Member

Registered: 2005-08-29

Posts: 3,588

Re: Algebra.

Father = 3Rohits
Father + 8 = 2.5(Rohits+8), Father + 8 = 2.5Rohits + 2.5(8), Father + 8 = 2.5Rohits + 20.
  Father = 2.5Rohits + 20 - 8, Father = 2.5Rohits + 12
2Fathers = 6Rohits
2Fathers = 5Rohits + 24
Subtract last two equations.
0 = 1Rohit - 24
Rohit = 24

Last edited by John E. Franklin (2007-06-12 10:34:35)

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mathsyperson

Moderator

Registered: 2005-06-22

Posts: 4,900

Re: Algebra.

Then you can use Rohit's age to find the age of his father. 3x24=72, so his father is 72.

Going forward 8 years gives that Rohit is 32 and his father is 80, and 32x2.5=80 so that works.
Going forward another 8 years gives that Rohit is 40 and his father is 88. At this point, his father is 2.2 times older than him.

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sk

Member

Registered: 2006-08-04

Posts: 19

Re: Algebra.

Yes... Thanks for the nice explanation John