Question

Pipe A fills a tank in 6 hours and pipe B fills it in 8 hours. How long will they take to fill the tank together?

Solution

1. A fills 1/6 of the tank per hour and B fills 1/8 per hour.
2. Combined rate = 1/6 + 1/8 = 7/24 tank per hour.
3. Time to fill one tank = 1 divided by 7/24 = 24/7 hours.
4. Therefore, they take 3 3/7 hours, or about 3 hours 26 minutes.