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It takes Computer A 36 hours to process data. If Computer A starts wor [#permalink]
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07 Aug 2008, 22:31
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It takes Computer A 36 hours to process data. If Computer A starts working at 7 pm on Monday and after half the data are processed Computer B, three times as fast as Computer A, joins in the task, when will the data processing be finished? A. 4:30 pm Tuesday B. 5:30 pm Tuesday C. 7:00 pm Tuesday D. 8:30 pm Tuesday E. 10:30 pm Tuesday M1812
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Re: It takes Computer A 36 hours to process data. If Computer A starts wor [#permalink]
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07 Aug 2008, 22:40
mba9now wrote: It would take Computer A 36 hours to process the data. If Computer A starts working at 7 pm on Monday and after half the data is processed Computer B, three times as fast as Computer A, is joined in the task, when will the data processing be finished?
4:30 pm Tuesday 5:30 pm Tuesday 7:00 pm Tuesday 8:30 pm Tuesday 10:30 pm Tuesday comp A takes 36h and comp B takes 12h comp A starts at 7pm on monday, processes half the data so it finishes at 7pm+(36/2)h which is 1pm on tuesday. Comp B takes up the next half so it finishes at 1pm+(12/2)h=7pm on Tuesday
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Re: It takes Computer A 36 hours to process data. If Computer A starts wor [#permalink]
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07 Aug 2008, 22:54
The answer is B (5:30 PM Tuesday). Becasue it is said that Comp B joins A, never says only B did the work alone.



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Re: It takes Computer A 36 hours to process data. If Computer A starts wor [#permalink]
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08 Aug 2008, 08:42
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mba9now wrote: It would take Computer A 36 hours to process the data. If Computer A starts working at 7 pm on Monday and after half the data is processed Computer B, three times as fast as Computer A, is joined in the task, when will the data processing be finished?
4:30 pm Tuesday 5:30 pm Tuesday 7:00 pm Tuesday 8:30 pm Tuesday 10:30 pm Tuesday computer A take 36 hr computer B takes 12 hr 18 hrs (half job done by computer) + Half job dont by both = 18 hrs + 18 / (3+1) = 22.5 hrs. B is the answer
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Re: It takes Computer A 36 hours to process data. If Computer A starts wor [#permalink]
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08 Aug 2008, 21:17
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mba9now wrote: It would take Computer A 36 hours to process the data. If Computer A starts working at 7 pm on Monday and after half the data is processed Computer B, three times as fast as Computer A, is joined in the task, when will the data processing be finished?
4:30 pm Tuesday 5:30 pm Tuesday 7:00 pm Tuesday 8:30 pm Tuesday 10:30 pm Tuesday work done by A in one hr = w/36 by B in 1 hr=w/12 by both in 1 hr=w/12 + w/36=w/9 hence half the work is already done by A in 18 hrs half the work w/2 is to be done by both hence time talken is w/2/w/9=9/2=4.5 hrs total time taken is 18+4.5 hrs=22.5 hrs 5.30pm tues is answer IMO B
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Re: It takes Computer A 36 hours to process data. If Computer A starts wor [#permalink]
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08 Aug 2008, 23:07
mba9now wrote: It would take Computer A 36 hours to process the data. If Computer A starts working at 7 pm on Monday and after half the data is processed Computer B, three times as fast as Computer A, is joined in the task, when will the data processing be finished?
4:30 pm Tuesday 5:30 pm Tuesday 7:00 pm Tuesday 8:30 pm Tuesday 10:30 pm Tuesday Total hrs = 18 + Hours required to do half job = 18 + (18*6)/24 = 22.5 hrs = 5:30pm Tue



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Re: It takes Computer A 36 hours to process data. If Computer A starts wor [#permalink]
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Re: It takes Computer A 36 hours to process data. If Computer A starts wor [#permalink]
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10 Nov 2014, 02:38
It takes Computer A 36 hours to process data. If Computer A starts working at 7 pm on Monday and after half the data are processed Computer B, three times as fast as Computer A, joins in the task, when will the data processing be finished?A. 4:30 pm Tuesday B. 5:30 pm Tuesday C. 7:00 pm Tuesday D. 8:30 pm Tuesday E. 10:30 pm Tuesday Computer A will process the first half of the data in 18 hours. Computer A and Computer B working together will process the remaining half four times quicker than will Computer A working alone. The entire task will require \(18 + \frac{18}{4} = 22.5\) hours which is 1.5 hours short of the 24hour cycle. If the processing commences at 7 pm on Monday, it will finish at 5:30 pm on Tuesday. Answer: B.
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Re: It takes Computer A 36 hours to process data. If Computer A starts wor [#permalink]
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12 Nov 2014, 02:25
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Rate of Computer A = \(\frac{1}{36}\) Rate of Computer B = \(\frac{1}{12}\) \(\frac{1}{2}\) Job completed by Computer A alone; means time consumed by Computer A \(= \frac{1}{2} * 36 = 18\) Hrs Combined rate of A & B \(= (\frac{1}{36} + \frac{1}{12}) = \frac{1}{9}\) Time required to complete remaining \(\frac{1}{2}\) Job \(= \frac{1}{2} * \frac{9}{1} = 4.5 Hrs\) Total Time required to complete job = 18 + 4.5 = 22.5 Hrs 24 Hrs is SAME TIME next day, so 22.5 Hrs would be 7PM Tuesday  1.5 Hrs = 5:30 PM Tuesday Answer = B
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Re: It takes Computer A 36 hours to process data. If Computer A starts wor [#permalink]
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20 Nov 2015, 14:22
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Re: It takes Computer A 36 hours to process data. If Computer A starts wor [#permalink]
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20 Dec 2015, 11:46
A= 1/36 B= 1/12 ( Ratio is 3:1 )
A+B= 1/9
HALF WORK DONE BY A only w=r*t 1/2 = 1/36*t t= 18 hrs
Rest work done by A & B together
w=r*T 1/2 = 1/9*T T= 4.5 hrs
Total Time= t+T
18+ 4.5 hrs = 22.5 hrs
Count from 7 pm Monday, answer is 5:30 pm Tuesday



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Re: It takes Computer A 36 hours to process data. If Computer A starts wor [#permalink]
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20 Dec 2015, 22:18
Step wise:
A: 36 hours B: 12 hours ( 3 times faster)
after half work done: 18 hours
W/2 left: Now W work can be done by both machines in 12*36/48 = 9 hours. So, W/2 cqan be done in 4.5 hours.
Total = 22.5 hours



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Re: It takes Computer A 36 hours to process data. If Computer A starts wor [#permalink]
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20 Dec 2015, 22:20
x2suresh wrote: mba9now wrote: It would take Computer A 36 hours to process the data. If Computer A starts working at 7 pm on Monday and after half the data is processed Computer B, three times as fast as Computer A, is joined in the task, when will the data processing be finished?
4:30 pm Tuesday 5:30 pm Tuesday 7:00 pm Tuesday 8:30 pm Tuesday 10:30 pm Tuesday computer A take 36 hr computer B takes 12 hr 18 hrs (half job done by computer) + Half job dont by both = 18 hrs + 18 / (3+1) = 22.5 hrs. B is the answer Hey, can you please explain how did you get 18/3+1 ?




Re: It takes Computer A 36 hours to process data. If Computer A starts wor
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