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Running at the same constant rate, a identical machines [#permalink]
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28 May 2017, 07:22
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Running at the same constant rate, a identical machines can produce a total of 120 bolts per minute. At this rate, how many bolts could 4 such machines produce in 5 minutes? (A) a/6 (B) a/600 (C) 150/a (D) 480/a (E) 2,400/a
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Re: Running at the same constant rate, a identical machines [#permalink]
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28 May 2017, 09:03
rohan2345 wrote: Running at the same constant rate, a identical machines can produce a total of 120 bolts per minute. At this rate, how many bolts could 4 such machines produce in 5 minutes?
(A) a/6 (B) a/600 (C) 150/a (D) 480/a (E) 2,400/a "a" identical machines can produce 120 bolts per minute. In 5 mins "a" machines can produce = 120 x 5 = 600 bolts
Therefore number of bolts produced by 4 such machines = \(\frac{600 * 4}{a}\) = \(\frac{2400}{a}\) Answer E...



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Re: Running at the same constant rate, a identical machines [#permalink]
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28 May 2017, 11:07
'a' machines in 1 minute = 120 bolts 'a' machines in 4 minutes = 5*120 = 600 bolts
This is a direct variation between number of bolts and number of machines. (greater the number of machines, greater the number of bolts produced) Let bolts produced by 4 such machines be 'x'
So we have a/4 = 600/x Or x = 2400/a
Hence E answer



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Running at the same constant rate, a identical machines [#permalink]
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Updated on: 29 Aug 2017, 10:47
rohan2345 wrote: Running at the same constant rate, a identical machines can produce a total of 120 bolts per minute. At this rate, how many bolts could 4 such machines produce in 5 minutes?
(A) a/6 (B) a/600 (C) 150/a (D) 480/a (E) 2,400/a 1. Find INDIVIDUAL RATE: W / (# of workers * time) = individual rate 120 / a*1 = 120/a 2. How many bolts produced by 4 machines in 5 minutes? Find TOTAL WORK given new # of machines and new time: (# of workers) * (individual rate) * (time) = total work 4 * 120/a * 5 = 2400/a Answer E
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Originally posted by generis on 28 May 2017, 15:31.
Last edited by generis on 29 Aug 2017, 10:47, edited 1 time in total.



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Re: Running at the same constant rate, a identical machines [#permalink]
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29 May 2017, 18:51
Hi rohan2345, This question can be solved by TESTing VALUES. We're told that a total of A machines (working together) will produce 120 bolts/minute. We're asked for the number of bolts that could be produced by 4 of these machines in 5 minutes. IF... A=2 Then 2 machines will produce those 120 total bolts/minute. Thus.... 4 machines will produce 240 bolts/minute. In 5 minutes, those 4 machines will produce (5)(240) = 1200 bolts So we're looking for an answer that equals 1200 when A=2. There's only one answer that 'fits'... Final Answer: GMAT assassins aren't born, they're made, Rich
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Re: Running at the same constant rate, a identical machines [#permalink]
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29 Aug 2017, 10:16
Nunuboy1994 wrote: EMPOWERgmatRichC wrote: Hi rohan2345, This question can be solved by TESTing VALUES. We're told that a total of A machines (working together) will produce 120 bolts/minute. We're asked for the number of bolts that could be produced by 4 of these machines in 5 minutes. IF... A=2 Then 2 machines will produce those 120 total bolts/minute. Thus.... 4 machines will produce 240 bolts/minute. In 5 minutes, those 4 machines will produce (5)(240) = 1200 bolts So we're looking for an answer that equals 1200 when A=2. There's only one answer that 'fits'... Final Answer: GMAT assassins aren't born, they're made, Rich EMPOWERgmatRichC Doesn't this problem belong in the work rate section? ______________________ Edited the tags. Thank you.
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Re: Running at the same constant rate, a identical machines [#permalink]
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29 Aug 2017, 10:21
easier to get confused without the appropriate highlight in the question part  Running at the same constant rate, a identical machines can produce a total of 120 bolts per minute. a machines > 120 1 machine > 120/a 4 machines > (120*4)/a above is all per minute, so for 5 minutes  (120*4*5)/a = 2400/a E
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Re: Running at the same constant rate, a identical machines [#permalink]
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01 Sep 2017, 12:00
rohan2345 wrote: Running at the same constant rate, a identical machines can produce a total of 120 bolts per minute. At this rate, how many bolts could 4 such machines produce in 5 minutes?
(A) a/6 (B) a/600 (C) 150/a (D) 480/a (E) 2,400/a We are given that the rate of a machines is 120. Thus, the rate of 4 machines is: a/120 = 4/x ax = 480 x = 480/a Since the rate of 4 machines is 480/a bolts per minute, 4 machines can produce 480/a * 5 = 2400/a bolts in 5 minutes. Answer: E
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