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July 5th, 2010, 09:59 AM   #1
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Proportion

I need a simple way to solve this question.

It takes 3 men to dig 2 identical trenches in 5 hours. If all the men work at the same rate, how long will it take 5 men to dig 7 of these trenches?

I have solved it this way through the help of an example in the book.

Solution

First we keep the number of trenches constant

No of men --- No of trenches --- No of Hours

3 --- 2 --- 5

1 --- 2 --- 5*3

5 --- 2 --- (5*3)/5=3

Next we keep the number of men constant


No of men --- No of trenches --- No of Hours
5 --- 2 --- 3

5 --- 1 --- 3/2=1.5

5 --- 7 --- 1.5*7=10.5

Therefore 5 men will take 10.5 hours to dig 7 identical trenches.


I want a simpler solution to this.
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July 5th, 2010, 10:23 AM   #2
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Re: Proportion

Hello Haftakan,

is constant.

In this case
In this case.

Will this do?

Hoempa
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July 5th, 2010, 01:49 PM   #3
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Re: Proportion

(number of trenches per man per 5 hours) * (number of men) * (number of 5 hour periods) = (number of trenches)

(2/3) * (5) * (x) = 7.
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