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A certain machine drills 30 holes in 8 minutes. At that constant rate,
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15 May 2018, 02:45
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A certain machine drills 30 holes in 8 minutes. At that constant rate,
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Updated on: 16 May 2018, 10:56
1 machine drills 30 holes in 8 minutes 1 machine drills 300 holes in 80 minutes. 80 minutes = \(1\frac{1}{3}\) hours 4 machines drill 300*4 = 1200 holes in 80 minutes Hence option D = 1200 is the answer.
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Originally posted by houston1980 on 15 May 2018, 02:50.
Last edited by houston1980 on 16 May 2018, 10:56, edited 1 time in total.



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Re: A certain machine drills 30 holes in 8 minutes. At that constant rate,
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15 May 2018, 02:57
Rate of one machine is \(\frac{(30 holes)}{(8 mins)}\) therefore, Rate of 4 machines is \(\frac{4 * (30 holes)}{(8 min)}\) = \(\frac{15 holes}{min}\) therefore total number of holes in \(\frac{4}{3} *60 mins\) = \(15 * 80\) = 1200 Answer is D
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Re: A certain machine drills 30 holes in 8 minutes. At that constant rate,
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15 May 2018, 03:35
Solution Given:• 1 machine drills 30 holes in 8 minutes To find:• How many holes will 4 such machines drill in 1\(\frac{1}{3}\) hrs (= \(\frac{4}{3}\) hrs = 80 minutes) Approach and Working: • 1 machine in 8 minutes drill 30 holes Or, 1 machine in 1minute drill \(30*\frac{1}{8}\) holes Or, 4 machines in 1minute drill \(30*\frac{1}{8}*4\) holes Or, 4 machines in 80 minutes drill \(30*\frac{1}{8}*4*80\) holes = 1200 holes Hence, the correct answer is option D. Answer: D
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Re: A certain machine drills 30 holes in 8 minutes. At that constant rate,
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15 May 2018, 03:37
Bunuel wrote: A certain machine drills 30 holes in 8 minutes. At that constant rate, how many holes will 4 such machines drill in \(1\frac{1}{3}\) hours?
(A) 300 (B) 900 (C) 960 (D) 1,200 (E) 2,560 First of, \(1\frac{1}{3}\) = 60 + 1/3*60 = 80 minutes
1 machine  8 minutes  30 holes (Rate = 30/8 holes per minute)
4 machines  80 minutes  30/8*80*4 holes
1200 (D)
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Re: A certain machine drills 30 holes in 8 minutes. At that constant rate,
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15 May 2018, 03:43
1 M drills 30 holes in 8 minutes 1 M will drills 300 holes in 80 minutes. 4 M will drill 300*4 = 1200 holes in 80 minutes
1200



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Re: A certain machine drills 30 holes in 8 minutes. At that constant rate,
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16 May 2018, 10:51
Bunuel wrote: A certain machine drills 30 holes in 8 minutes. At that constant rate, how many holes will 4 such machines drill in \(1\frac{1}{3}\) hours?
(A) 300 (B) 900 (C) 960 (D) 1,200 (E) 2,560 The rate of one machine is 30/8 = 15/4 holes per minute, so the rate of 4 machines is 4 x 15/4 = 15 holes per minute. Since 1 1/3 hours = 80 minutes, the 4 machines can drill 15 x 80 = 1200 holes. Answer: D
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Re: A certain machine drills 30 holes in 8 minutes. At that constant rate,
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03 Oct 2018, 01:07
A machine drills hole per min= 30/8 (holes/min) In 4/3 hours= 80 mins=30*80/8= 300 holes
So, 4 machines drill holes in 4/3 hrs= 300*4= 1200 holes
(D)




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