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15 Jan 2024, 02:30
Kudos
Bookmarks
C
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
15%
(low)
Question Stats:
88% (01:54) correct
12%
(02:30)
wrong
based on 205
sessions
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Not Attempted Yet
Machine A can complete a job in 12 hours, and Machine B can do the same job at 1/5 of the rate of Machine A. If Machine A completes 3/4 of the job and then Machine B finishes the remaining portion, what is the total amount of time taken by Machine A and Machine B?
(A) 18 hours
(B) 20 hours
(C) 24 hours
(D) 28 hours
(E) 30 hours
(A) 18 hours
(B) 20 hours
(C) 24 hours
(D) 28 hours
(E) 30 hours
Machine A can do a job in 12 hours at a constant rate and Machine B can do the same job at a 1/5 constant rate of machine A. If machine A does 3/4 of the job and then machine B do the rest of the job, what is the total amount of hours done by machine A and machine B?
Bunuel
OA is C
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15 Jan 2024, 08:03
Kudos
Bookmarks
Bunuel
Let total work be 60 units...
Efficiency of A is 5 units/hr, Efficiency of B is 1 unit/hour
Work completed by A is 3/4*60 = 45 Units, thus 15 units are left....
Time required by A to complete 45 units is 45/5 = 9 Hours...
Time required by B to complete 15 units is 15/1 = 15 Hours...
SO, Total Time taken is 9 +15 = 24, Answer must be (C)
