A boat moves at 9 km/h in still water, and the stream flows at 3 km/h. How long does it take to go 24 km upstream and come back?

4 hoursCorrect answerYour answer

\frac{16}{3}

hoursCorrect answerYour answer6 hoursCorrect answerYour answer8 hoursCorrect answerYour answer

Show the answer and explanation

CorrectNot quiteAnswer C

Correct answer: C

Upstream at $9 - 3 = 6$ km/h takes $\frac{24}{6} = 4$ hours; downstream at 12 km/h takes 2 hours.
In all, 6 hours.

Worth noting

$\frac{16}{3}$ hours is 48 km at the still-water speed, ignoring the stream.

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

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

Explanation