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Re: If a copier makes 3 copies every 4 seconds, then continues at this rat [#permalink]

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26 Jul 2016, 11:15

Top Contributor

Bunuel wrote:

If a copier makes 3 copies every 4 seconds, then continues at this rate, how many minutes will it take to make 9,000 copies?

A. 60 B. 100 C. 120 D. 200 E. 3,000

We can solve the question using EQUIVALENT RATIOS

(# copies)/(seconds) Let x = seconds to make 9000 copies. We get: 3/4 = 9000/x Cross multiply to get: 3x = (4)(9000) Simplify: 3x = 36,000 Solve: x = 12,000 SECONDS

There are 60 seconds in a minute. 12,000/60 = 200 So, it takes 200 MINUTES to make 9000 copies

Re: If a copier makes 3 copies every 4 seconds, then continues at this rat [#permalink]

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09 Apr 2018, 07:22

Top Contributor

Bunuel wrote:

If a copier makes 3 copies every 4 seconds, then continues at this rate, how many minutes will it take to make 9,000 copies?

A. 60 B. 100 C. 120 D. 200 E. 3,000

Another approach is to apply some number sense in a series of steps

GIVEN: Copier makes 3 copies every 4 seconds So: the copier makes 45 copies every 60 seconds [if we increase the working time by a factor of 15, then the number of copies increases by a factor of 15] In other words, the copier makes 45 copies every 1 MINUTE [60 seconds = 1 MINUTE] Keep going: the copier makes 9000 copies every 200 MINUTES [if we increase the working time by a factor of 200, then the number of copies increases by a factor of 200]

Answer: D

Cheers, Brent
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Brent Hanneson – Founder of gmatprepnow.com

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Re: If a copier makes 3 copies every 4 seconds, then continues at this rat
[#permalink]
09 Apr 2018, 07:22