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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
 

#3 2006-03-11 17:36:14

ganesh
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Re: Average

http://www.dormy.co.uk/library/Office/Mates/Classmates/images/CM2_VeryGood.jpg


Character is who you are when no one is looking.
 

#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! smile


Character is who you are when no one is looking.
 

#6 2009-01-05 11:24:46

JaneFairfax
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Re: Average

A # 2






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

A: Click here for answer.
 

#7 2009-02-07 22:39:05

JaneFairfax
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Re: Average


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

A: Click here for answer.
 

#8 2010-04-19 17:15:38

keveenjones
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Re: Average

The weight of person A is 72.

 

#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.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.
 

#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.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.
 

#13 2011-03-01 16:34:15

G-man
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Re: Average

[hide=A's weight]85kg[hide/]


Maths!......sleep
 

#14 2011-03-01 20:12:39

bobbym
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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.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.
 

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