vinni.k wrote:"A" alone can complete a work in 16 days and "B" alone in 12 days. Starting with "A", they work on alternate days. The total work will be completed in:
(a). 12 days
(b). 13 days
(c). 13(5/7) days
(d). 13(3/4) days
(e). none
OA is D
Let the job = the LCM of 16 and 12 = 48 units.
A's rate = w/t = 48/16 = 3 units per day.
B's rate = w/t = 48/12 = 4 units per day.
When A and B alternate, the amount of work produced every 2 days = 3+4 = 7 units.
Thus, after 2*6 = 12 days, the amount of work produced = 7*6 = 42 units.
Amount of work remaining after 12 days = 48-42 = 6 units.
On the 13th day, A produces 3 more units.
Amount of work remaining after 13 days = 6-3 = 3 units.
Time for B to complete the remaining 3 units = w/r = 3/4 days.
Total time = 13 + 3/4 = 13.75 days.
The correct answer is
D.
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