Correct Answer: 6 days
Explanation:
M = 10 days
The ratio of efficiency of M & N are 3 : 2
Hence, the time rquired for N alone = 15 days
=> Required time taken t=by both to complete the work = M x N / M + N
= 10 x 15/ 10 + 15
= 150/25
= 6 days.
