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#1 2013-02-03 04:16:57
- Al-Allo
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Proportion
I just have a little problem :
X 8
_= _
7 9
If I would want to solve for X, I would multiply by 7 for each side. Leaving x=56
___
9
But what I did is x=56
__
63
Could somebody explain me why it's wrong ?
Thanks
#2 2013-02-03 05:26:06
- bobbym
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Re: Proportion
When you multiply by 7 you cancel the 7 on the left but not the 9 on bottom right.
Correct thing to do is to cross multiply
9x = 56
x = 56 / 9
In mathematics, you don't understand things. You just get used to them.
Probability is the most important concept in modern science, especially as nobody has the slightest notion what it means.
90% of mathematicians do not understand 90% of currently published mathematics.
#3 2013-02-03 05:30:18
- Al-Allo
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Re: Proportion
But I mean not canceling the 9 but multiplying it by 7, it's not a right thing to do ? Thanks
#4 2013-02-03 05:34:45
- bobbym
- Administrator
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Re: Proportion
If you multiply by 7 you are going to get:
x = 56 / 9 which is the same thing.
In mathematics, you don't understand things. You just get used to them.
Probability is the most important concept in modern science, especially as nobody has the slightest notion what it means.
90% of mathematicians do not understand 90% of currently published mathematics.
#5 2013-02-03 06:28:41
- Al-Allo
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Re: Proportion
bobbym wrote:
If you multiply by 7 you are going to get:
x = 56 / 9 which is the same thing.
ok, I understood. Thanks
Last edited by Al-Allo (2013-02-03 06:30:14)
#6 2013-02-03 06:32:09
- bobbym
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Re: Proportion
Hi;
You are welcome.
In mathematics, you don't understand things. You just get used to them.
Probability is the most important concept in modern science, especially as nobody has the slightest notion what it means.
90% of mathematicians do not understand 90% of currently published mathematics.