Solution:
Given:
A can complete the work in 14 days
B can complete the work in 21 days
Concept:
In this type of question always imagine the total work as LCM of time taken by individuals to perform the work.
Formula used:
Efficiency = Total work/Time taken
Calculation:
Let the total work be LCM of 21, 14 i.e 42 unit
So, Efficiency of A = 42/14 = 3 unit/day
Efficiency of B = 42/21 = 2 unit/day
Efficiency of (A + B) = 5 unit/day
According to Question,
A and B work for 4 days and performed work = 4 × 5 = 20 unit
Remaining work left = 42 – 20 = 22 unit
B completes the remaining work = 22/2 = 11 days
∴ Time taken by B to complete the remaining work is 11 day
