Question 36
A and B together can complete a work in 12 days. A alone can complete it in 20 days. If B does the work only for half a day daily then in how many days A and B together will complete the work?
Solution
Let us assume the total work = 60 units.
Efficiency of A = 60/20 = 3 units per day.
Efficiency of A and B together = 60/12 = 5 units per day.
Efficiency of B = 5 - 3 = 2 units per day.
Now B works for only half a day which implies that B's efficiency becomes 2/2 = 1 unit per day.
Combined efficiency of A and B = 3+1 = 4 units per day.
Time taken to finish the work = 60/4 = 15 days.
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