Practice30 Create account

Both inlets in the figure are opened on the empty tank. How long will it take to fill?

Competition practicePipes & Cisterns

A4.5 h
B6 h
C13.5 h
D27 h

Step-by-Step Solution

Per hour:

\frac{1}{18} + \frac{1}{9} = \frac{1 + 2}{18} = \frac{1}{6}

→ 6 h. (13.5 h is the average of the times, 27 h their sum.)

Answer: B) 6 h

Master this topic in 30 minutes a day.

Don't just memorise the answer — build a daily practice habit.

Practice 5 Similar Questions Free →

All Pipes & Cisterns practice questions

More Pipes & Cisterns practice

An inlet fills a sump in 25 minutes and an outlet drains it in 50 minutes. Opened…Six equal pipes fill a swimming pool in 20 hours. If only four of them are used, how…Taps A, B and C fill a tank in 10, 20 and 30 minutes respectively. If all three are…An overhead tank holds 3,600 litres. Pipe A delivers 30 litres per minute and pipe B…A pipe fills 2/5 of a tank in 8 minutes. How long would it take to fill the whole tank?