Working alone A can do a work in 72 days and B in 90 days. If they work on it together for 10 days, then what fraction of work is left?
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4 i.e. 3/4
|
Understanding |
Application |
|
Working alone A can do a work in 72 days and B in 90 days. |
Suppose total work = 360 units (LCM of 72 and 90) So, Efficiency of A = 360/72 = 5 Efficiency of B = 360/90 = 4 Hence, Time in which A and B together can finish the whole work = 360/(5 + 4) = 40 days Hence, Fraction of work done in 10 days = 10/40 = 1/4 So, Work left = 1 – 1/4 = 3/4 |