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

ganesh
Moderator
Registered: 2005-06-28
Posts: 14,843

### 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

Member
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
Moderator
Registered: 2005-06-28
Posts: 14,843

### Re: Average

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
Moderator
Registered: 2005-06-28
Posts: 14,843

### Re: Average

Well done, thinkdesigns!

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?

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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?

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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
From: Bumpkinland
Registered: 2009-04-12
Posts: 88,931

### 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 agree with you regarding the satisfaction and importance of actually computing some numbers. I can't tell you how often I see time and money wasted because someone didn't bother to run the numbers.

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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: 14,843

### 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
From: Bumpkinland
Registered: 2009-04-12
Posts: 88,931

### 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 agree with you regarding the satisfaction and importance of actually computing some numbers. I can't tell you how often I see time and money wasted because someone didn't bother to run the numbers.

Online

## #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!......

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

bobbym
From: Bumpkinland
Registered: 2009-04-12
Posts: 88,931

### 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 agree with you regarding the satisfaction and importance of actually computing some numbers. I can't tell you how often I see time and money wasted because someone didn't bother to run the numbers.

Online