Pipes A, B and C can fill a tank in 10, 12 and 15 hours respectively. How long do the three take together?

2 hoursCorrect answerYour answer3 hoursCorrect answerYour answer4 hoursCorrect answerYour answer

\frac{37}{3}

hoursCorrect answerYour answer

Show the answer and explanation

CorrectNot quiteAnswer C

Correct answer: C

Per hour: $\frac{1}{10} + \frac{1}{12} + \frac{1}{15} = \frac{6 + 5 + 4}{60} = \frac{15}{60} = \frac{1}{4}$ of the tank.
So together they take 4 hours.

Worth noting

$\frac{37}{3}$ hours is the average of 10, 12 and 15, longer than the fastest pipe alone.

Ten questions from Boats & Streams, Pipes & Cisterns, at your own pace.

Ten questions from Boats & Streams, Pipes & Cisterns, at your own pace.

Explanation