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#1 2008-12-02 07:19:37

tony123
Member
Registered: 2007-08-03
Posts: 189

how old is jane now?

jane and olivia both celebrate their birthday today. In three years, jane
will be four times as old as olivia  was when jane was two years older than
olivia  is today. If olivia  is a teenager, how old is jane now?

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#2 2008-12-02 08:23:13

JaneFairfax
Member
Registered: 2007-02-23
Posts: 6,868

Re: how old is jane now?


Q: Who wrote the novels Mrs Dalloway and To the Lighthouse?

A: Click here for answer.

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#3 2010-12-09 00:43:05

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 87,258

Re: how old is jane now?

This is a nice problem that I found while looking through the oldies here. I know this has already been answered by Jane which seems apt. I still enjoyed working on it.

We call the variables:

Agediff - the difference between Jane's and Olivia's ages.
Jage      Jane's age now, what we want.
Oage     Olivia's age now.
Jthen     Jane's age then ( 2 years older than olivia is now )
Othen    Olivia'a age when Jane was 2 years older.

We get the following equations.

Eliminating Jthen:

Eliminating Agediff:

Eliminating Othen:

Easy to solve:

Jage = Jane's age = 25
Oage = Olivia's age = 15


In mathematics, you don't understand things. You just get used to them.
Of course that result can be rigorously obtained, but who cares?
Combinatorics is Algebra and Algebra is Combinatorics.

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#4 2011-01-07 09:14:33

gurthbruins
Member
Registered: 2010-05-09
Posts: 157

Re: how old is jane now?

A fun problem. My solution:


It's the activity of the intelligence above all that gives charm to existence.

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