RRB NTPC · Question 35
'A' can complete a piece of work in 20 days and 'B' alone can complete the work in 30 days. Due to some other work, 'A' had to leave the work before completion and for the last 5 days 'B' alone did the work. The total time taken to complete the work is:
Show answer & explanation
Answer: (D) 15 days
Explanation
B alone does 5/30 = 1/6 in the last 5 days, so 5/6 was done together at 1/20 + 1/30 = 1/12 per day – 10 days. Total = 10 + 5 = 15 days.