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#1 2006-03-11 15:35:17
- ganesh
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Average
A # 1
The average weight of three men A, B, and C is 84 kg. A fourth man D joins them and the average weight of the four becomes 80 kg. If E whose weight is 3 kg more than D replaces A, then the average weight of B, C, D, and E becomes 79 kg. Find the weight of A.
Character is who you are when no one is looking.
#2 2006-03-11 17:24:00
- darthradius
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Re: Average
The greatest challenge to any thinker is stating the problem in a way that will allow a solution.
-Bertrand Russell
#4 2006-04-22 05:13:52
- thinkdesigns
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Re: Average
Not sure but
A+B+c=252 ( average of 84*3) eq1
A+b+c+d=320 eq2
eq1 -eq2
d=68
b+c+d+e=316 eq3
e=d+3
sub into eq3
b+c+2d+3=316 eq4
eq2-eq4
A-d-3=4
a=d+7
(knowing d is 68)
a=75
#5 2006-04-22 14:28:34
- ganesh
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Re: Average
Well done, thinkdesigns! 
Character is who you are when no one is looking.
#6 2009-01-05 11:24:46
#7 2009-02-07 22:39:05
- JaneFairfax
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#9 2010-04-19 17:49:38
- bobbym
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Re: Average
Hi keveenjones;
Welcome to the forum!
You get 3 equations in 4 unknowns:
Clear out fractions:
Subtract 1 from 2 and you get:
D = 68. Now use that in 2 and 3:
Subtract 2 from 1
A = 75.
In mathematics, you don't understand things. You just get used to them.
90% of mathematicians do not understand 90% of currently published mathematics.
I am willing to wager that over 75% of the new words that appeared were nothing more than spelling errors that caught on.
#10 2010-08-17 14:18:46
- jonnyj99
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Re: Average
There are many different types of equation for find the average. I give the easy equation are given the below.
y = f^{-1}\left(\frac{f(x_1)+f(x_2)+\cdots+f(x_n)}{n}\right),
#11 2010-08-17 19:18:38
- ganesh
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Re: Average
Hi jonnyj99,
The posts are understood better with LaTeX.
Character is who you are when no one is looking.
#12 2010-08-17 19:36:14
- bobbym
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Re: Average
Hi jonnyj99;
Welcome to the forum!
Ganesh is right. You forgot the math tags on both ends of your latex.
In mathematics, you don't understand things. You just get used to them.
90% of mathematicians do not understand 90% of currently published mathematics.
I am willing to wager that over 75% of the new words that appeared were nothing more than spelling errors that caught on.
#14 2011-03-01 20:12:39
- bobbym
- Administrator
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Re: Average
Hi G-man;
That is close but the answer is 75, please see post #9.
In mathematics, you don't understand things. You just get used to them.
90% of mathematicians do not understand 90% of currently published mathematics.
I am willing to wager that over 75% of the new words that appeared were nothing more than spelling errors that caught on.