Category: Mathematics | Last updated: 2026-09-18

Two pipes can fill a tank in 12 and 15 hours respectively. How long will it take to fill the tank if both pipes are opened together?

A) 6 hours 40 min

B) 5 hours 30 min

C) 7 hours

D) 6 hours

Explanation

Combined rate = 1/12 + 1/15 = 9/60 = 3/20. Time = 20/3 = 6 hrs 40 min.