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#1 2006-03-10 16:35:17

ganesh
Moderator
Registered: 2005-06-28
Posts: 13,282

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.

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#2 2006-03-10 18:24:00

darthradius
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Registered: 2005-11-28
Posts: 97

Re: Average


The greatest challenge to any thinker is stating the problem in a way that will allow a solution.
                                                             -Bertrand Russell

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#3 2006-03-10 18:36:14

ganesh
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Registered: 2005-06-28
Posts: 13,282

Re: Average

CM2_VeryGood.jpg


Character is who you are when no one is looking.

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#4 2006-04-21 07:13:52

thinkdesigns
Member
Registered: 2005-07-21
Posts: 23

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

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#5 2006-04-21 16:28:34

ganesh
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Registered: 2005-06-28
Posts: 13,282

Re: Average

Well done, thinkdesigns! smile


Character is who you are when no one is looking.

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#6 2009-01-04 12:24:46

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

Re: Average

A # 2


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

A: Click here for answer.

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#7 2009-02-06 23:39:05

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

Re: Average


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

A: Click here for answer.

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#8 2010-04-18 19:15:38

keveenjones
Member
Registered: 2010-04-18
Posts: 2

Re: Average

The weight of person A is 72.

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#9 2010-04-18 19:49:38

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 83,251

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.

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#10 2010-08-16 16:18:46

jonnyj99
Member
Registered: 2010-08-16
Posts: 4

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),

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#11 2010-08-16 21:18:38

ganesh
Moderator
Registered: 2005-06-28
Posts: 13,282

Re: Average

Hi jonnyj99,

The posts are understood better with LaTeX.


Character is who you are when no one is looking.

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#12 2010-08-16 21:36:14

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 83,251

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.

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#13 2011-02-28 17:34:15

G-man
Member
Registered: 2011-02-28
Posts: 16

Re: Average

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


Maths!......sleep

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#14 2011-02-28 21:12:39

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 83,251

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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