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Machine problem

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Master | Next Rank: 500 Posts
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by moneyman » Sun Oct 21, 2007 2:48 am
Six machines each working at the same constant rate together can complete a given job in 12 days.How many additional machines , each working at the same constant rate,will be needed to complete the job in 8 days??

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Maxx
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by zacky » Sun Oct 21, 2007 3:33 am
Hello,

I think you have to calculate how percentage of evolution of machines you need comparing to the time reduction ration.

Time reduction ratio : 12 days / 8 days = 1.5
Than 6 machines * 1.5 = 9 machines

Finally you need to add 3 machines.

Am I right ?

Zacky
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by jimbow » Sun Oct 21, 2007 12:53 pm
Other possibility:

6 machines for 12 days
3 machines for 24 days
1 machines for 72 days

thus
1x9 machines for 72/9=8 days
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by wongee » Mon Oct 22, 2007 7:00 pm
Another:

Mach Days
6 12
x 8

Inverse proportion = to finish in LESS days we need MORE machines

6 * 12/8 = 9

(9-6) = 3 additional machines
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