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November 24th, 2014, 02:56 AM   #1
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Lesson on direct and indirect proportion

Hi I have a question:

"It takes two electricians 9 days to rewire two house. How long would it take 3 electricians to rewire 3 of the same houses at the same rate?".

I dont want the answer. I would like someone to point me to a decent lesson on this subject so I can understand.

Any help?
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November 24th, 2014, 05:34 AM   #2
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Let's imagine that the first electrician rewires the first house, and the second electrician rewires the second house. It takes 9 days. Now let's forget second one, and watch just the first electrician. Certainly, it will take 9 days for him to rewire one house.
So, 3 electricians rewire 3 houses 9 days, and for any n, it takes n electricians 9 days to rewire n houses.
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