M can do a piece of work in 12 days and N in 24 days. They begin together, but M leaves the work 6 days before the completion of the work. Find the total number of days to complete the entire work.
Show answer & explanation
Correct answer: B
Explanation
The correct answer is option 2 i.e. 12 days.
M can do a piece of work = 12 days
N can do a piece of work = 24 days
Let's assume the total work = LCM of 12 and 24 = 24
Efficiency = Total work/Total time
So, efficiency of M = 24/12 = 2 unit per day
Efficiency of N = 24/24 = 1 unit per day
Their 6 days work = (2 + 1) × 6 = 18
Remaining work done by N = (24 - 18)/1 = 6 days
So, total days to finish the work = 6 + 6 = 12 days