A and B working alone can finish a job in 5 days and 7 days respectively. They work at it alternately for a day. If A starts the work, find in how many days the job will be
finished?
a) 29/5
b) 11/5
c) 24/5
d) 21/5
e) None of these

1 Answer

Answer :

Work done by A in one day = 1/5 and work done by B in one day = 1/7
They are working alternately.
Therefore, Work done in first two day = (1/5 + 1/7) = 12/35
Work done in first four day = 24/35
Work done in first 5 days = 24/35 + 1/5 = 31/35
Remaining work = 4/35
Day it will take B to complete = 4/35/1/7 = 4/5 of the day.
Therefore Total days taken = 5 + 4/5 = 29/5 days
Answer: b)

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