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Twelve identical machines, running continuously at the same

1 2

kaylaquijas

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17 Nov 2021, 09:09

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EMPOWERgmatRichC

Hi kaylaquijas,

The type of equation that you've set up can be used in a couple of different ways (for example, to reduce a fraction or 'scale up' a recipe). However, in this type of 'work' question, this equation does NOT apply. To answer the given question, we need to be thinking in terms of the TOTAL amount of work that's needed to be done - and based on the given information, we know that it takes 12 machines working 8 days each to complete a task. That's (12)(8) = 96 machine-days of work. Whatever equation you choose to create, you have to account for THAT outcome.

GMAT assassins aren't born, they're made,
Rich

Contact Rich at: [email protected]

Thanks EMPOWERgmatRichC,

I now understand why I can't use a standard ratio to set this up. I have spent three hours on this one problem, but I now understand how to solve it. Hopefully, this time sink pays off!

thesip2323

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Sat on this question for a while because I read the last two words as "to 2 days" rather than "by 2 days". Can't believe one word can be so critical.

Anyway, I used the proportion method:

12 workers / 1/8 = X workers / 1/6 (not 1/2 as I initially thought) --> Cross multiply to get 2 = X/8 --> X = 16, therefore, 16-12 = 4 additional workers required.

chloreton

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03 Apr 2026, 00:28

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Since work done is constant in both,
8*12 = 6*(12+x)
x = 4

Option C

Adit_

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Since all identical rates, Two reduce the number of days by 2 or completing in 6 days:
We multiple 8*6/8 to get 6 days and multiple the reciprocal to the machines = 12*8/6 = 16
Thus 4 more machines needed.

Answer: Option C

gsaxena26

Twelve identical machines, running continuously at the same constant rate, take 8 days to complete a shipment. How many additional machines, each running at the same constant rate, would be needed to reduce the time required to complete a shipment by two days?

A. 2
B. 3
C. 4
D. 6
E. 9