Bunuel wrote:

Official Solution:

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 24-hour cycle. If the processing commences at 7 pm on Monday, it will finish at 5:30 pm on Tuesday.

Answer: B

How is B possible when it is clearly mentioned that B is 3 times faster;B should take 6 hours to complete the remaining job i.e. 18/3=6 hours and not 18/4=4.5 Hours........

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