Q. A and B working separately can complete a piece of work in 9 and 12 days
respectively. If they work alternatively starting from A in how many days will the work
completed?
A. 10.25 days B. 11.5 days
Answer A
C. 12.75 days
D.9 days
Fynlanation: Atakes 9 days to complete a piece of work. B takes 12 days to
Answers
Answer:
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Step-by-step explanation:
A does the work in 9 days, so in 1 day A does 1/9 units of the work. Similarly B does 1/12 units of work in a day.
If they start working alternately, starting with A, then in each shift(i.e. A works on 1st day and B on 2nd day. So a shift means 2 days), they do 1/9 + 1/12 = 7/36 units of work in 2 days. So in 5 shifts i.e. in 10 days total amount of work done is 5*7/36 = 35/36 units of work.
So after 10 days 35/36 units of work is over. Amount of work left for 11th day is 1–35/36 = 1/36 and it is A’s turn to work. A does 1/9 units of work in 1 day so he will finish the remaining 1/36 units in 1/4 of a day or 6 hours.
Therefore total amount of time taken is 10 + 1/4 = 41/4 days or 10 days and 6 hours.