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Specialty Chemistry Forums => Other Sciences Question Forum => Topic started by: Borek on April 09, 2006, 05:04:44 AM

Title: Grandpa and Grandma age?
Post by: Borek on April 09, 2006, 05:04:44 AM: Granpda and Grandma have 126 years togehter. How old is Grandma and how old is Grandpa, if Grandpa is twice older then Grandma was when Grandpa was as old as Grandma is now?
Title: Re: Grandpa and Grandma age?
Post by: Mitch on April 09, 2006, 05:08:09 AM: Grandpa is still alive?
Title: Re: Grandpa and Grandma age?
Post by: Borek on April 09, 2006, 05:12:27 AM: Most likely :)
Title: Re: Grandpa and Grandma age?
Post by: xiankai on April 09, 2006, 05:18:09 AM: grandma = x

(...)

grandma is ** years old, grandpa is ** years.

nice one borek, it really got me thinking.
Title: Re: Grandpa and Grandma age?
Post by: Borek on April 09, 2006, 05:39:15 AM: xiankai - OK,

I have edited your post, to not spoil fun for others ;)
Title: Re: Grandpa and Grandma age?
Post by: pantone159 on April 09, 2006, 05:56:03 PM: That was kind of a tongue-twister for the brain. At least Grandma Xena thought so, but 'Harrumf' said Grandpa.
Title: Re: Grandpa and Grandma age?
Post by: Hunt on April 11, 2006, 06:09:45 PM: x = ganrdma's present age , y = grandpa's present age

(deleted)

Grandpa is ** yrs old and Grandma's ** yrs old , they're not that old afterall :P
Title: Re: Grandpa and Grandma age?
Post by: Borek on April 11, 2006, 06:19:42 PM: Right :)

Post edited as usual ;)
Title: Re: Grandpa and Grandma age?
Post by: constant thinker on April 11, 2006, 07:39:13 PM: All it is is a simple system of equations.

http://www.1728.com/unknwn2.htm <- A nice calculator for this.

I would put the answers, but I'll save Borek the work of erasing it. ;)
Title: Re: Grandpa and Grandma age?
Post by: Hunt on April 12, 2006, 09:21:23 AM: Solving a system of 2 equations 2 unknowns isn't the difficult part, but rather establishing the equations, If you understand the question, it becomes very easy .
Title: Re: Grandpa and Grandma age?
Post by: Borek on April 12, 2006, 09:33:07 AM: It can be done with one unknown as well.
Title: Re: Grandpa and Grandma age?
Post by: constant thinker on April 12, 2006, 03:17:38 PM: Good point. If you just find 1 <.> of 126 then you can figure it out from there.
Title: Re: Grandpa and Grandma age?
Post by: Hunt on April 12, 2006, 07:25:08 PM: You can even solve it by trial and error.
Title: Re: Grandpa and Grandma age?
Post by: Borek on April 12, 2006, 07:35:42 PM: Quote from: Vant_Hoff on April 12, 2006, 07:25:08 PM
You can even solve it by trial and error.

Not before understanding the question :)
Title: Re: Grandpa and Grandma age?
Post by: FeLiXe on April 13, 2006, 11:24:44 AM: I have it

but I won't spoil it
Title: Re: Grandpa and Grandma age?
Post by: Donaldson Tan on April 21, 2006, 12:25:36 PM: LOL. One just have to travel back in time by (x-y) years, where x is grandpa's age and y is grandma's age.
Title: Re: Grandpa and Grandma age?
Post by: Bakegaku on April 21, 2006, 09:24:58 PM: admittedly I had to write some stuff down for this one ;)

hmmm... no spoil tags on this forum. Oh well. I'll just space down a few times and hope Borek sees it fast so no one has their answer spoiled (assuming mine is right... ;D)

[stuff deleted by Borek as usuall...]
Title: Re: Grandpa and Grandma age?
Post by: swati on June 24, 2006, 05:32:49 PM: Grandpa's Age = 75.6 yrs
Grandma's Age = 50.4 yrs

;) It was not a difficult one.
Title: Re: Grandpa and Grandma age?
Post by: Borek on June 24, 2006, 05:51:12 PM: Quote from: swati on June 24, 2006, 05:32:49 PM
Grandpa's Age = 75.6 yrs
Grandma's Age = 50.4 yrs

;) It was not a difficult one.

It was - this is not correct answer. Both ages are integer numbers.
Title: Re: Grandpa and Grandma age?
Post by: billnotgatez on June 24, 2006, 07:26:24 PM: Is this a fall spring marriage?
Title: Re: Grandpa and Grandma age?
Post by: swati on June 25, 2006, 12:40:42 PM: Borek , please tell me my mistake :)

I have done it the following way
Grandpa's age = x yrs
Grandma's age = y yrs
x + y = 126 ---------- ( 1 )

(x-y) yrs ago
Grandpa's age = x - ( x - y) yrs = y yrs
Grandma's age = [ y - ( x - y) ] yrs = [ 2y - x ] yrs
y = 2 [ 2y - x ]
=> y = 4y - 2x
=> 2x - 3y = 0 --------- ( 2 )
Multiplying ( 1 ) by 3 & then adding it to ( 2 ) , we get
5x = 378
=> x = 75.6 yrs
And y = 50.4 yrs
Title: Re: Grandpa and Grandma age?
Post by: Will on June 25, 2006, 01:22:03 PM: This is the correct equation:
x = 2(y-(x-y))
which gives 4y-3x=0

Then you can put that into x+y=126
Title: Re: Grandpa and Grandma age?
Post by: swati on June 25, 2006, 07:08:49 PM: Quote from: Will on June 25, 2006, 01:22:03 PM
This is the correct equation:
x = 2(y-(x-y))
which gives 4y-3x=0

Then you can put that into x+y=126

:( Sorry I have made such a stupid mistake.

correct result deleted as usual ;)
Title: Re: Grandpa and Grandma age?
Post by: technologist on June 26, 2006, 01:22:04 AM: Borek,

Grand Pa will be a decade short in a century after the no of years the difference is there in their age.
Title: Re: Grandpa and Grandma age?
Post by: hmx9123 on June 26, 2006, 03:46:22 AM: And if we go with the 'half plus seven rule' which states that the youngest person you can date is half your age plus seven years, grandpa currently sits within the limits. So the next question is: at what age did grandpa finally fit that rule? :) Then we should compare that to when they got married. Sounds like grandma might be a gold digger (i.e., Anna Nicole Smith).