A can complete work in 25 days and B can complete the same work in 20 days. They started the work together but B left after 4 days and A continued to work. In how many days will the entire work be completed?
Show answer & explanation
Correct answer: B
Explanation
The correct answer is option 2 i.e. 20
Time in which A can complete the work = 25 days
Time in which B can complete the work = 20 days
Time for which B worked = 4 days
Total work = L.C.M of 20 and 25 = 100 units
Amount of work done by A in one day = 100/25 = 4 units
Amount of work done by B in one day = 100/20 = 5 units
Total work done by both of them in four days = (4 × 4 + 5 × 4) = 16 + 20 = 36
Remaining work = 100 - 36 = 64 units
Remaining work is done by A alone in = 64/4 = 16 days
Total time taken to complete the work = 16 + 4 = 20 days