A can do a work in 20 days and B in 30 days. If they work on it together for 2 days, then what is the fraction of the work that is left?
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4 i.e
A can do a work in 20 days.
B can do the same work in 30 days.
Total work = L.C.M of 20 and 30 = 60 units
Amount of work done by A in a day = 60/20 = 3 units
Amount of work done by B in a day = 60/30 = 2 units
Amount of work done by A and B together in 2 days = 2 × (3 + 2) = 10 units
Amount of work still left = 60 - 10 = 50units
Fraction of work that is left = 50/60 = 5/6