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Boats & Streams, Pipes & Cisterns · Question 7 of 85

What is the speed of the river's current?

Question 7

EasyOriginal question

A ferry runs between two jetties 24 km apart on a river. It makes the trip downstream in 2 hours and the trip back upstream in 3 hours.

What is the speed of the river's current?

2 km/hCorrect answerYour answer3 km/hCorrect answerYour answer4 km/hCorrect answerYour answer10 km/hCorrect answerYour answer

Show the answer and explanation

CorrectNot quiteAnswer A

Correct answer: A

The current adds to the speed one way and takes it away the other.
$\frac{12 - 8}{2} = 2$ km/h.

Worth noting

4 km/h is the whole difference, twice the current.

Concept: Speed of the stream
Typical timeTypical: 90 s
Your timeYours: —

The rule this testsUpstream and downstream speeds

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