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Boats & Streams, Pipes & Cisterns · Question 21 of 85

Question 21

HardOriginal question

A man takes twice as long to row a distance upstream as to row it downstream. What is the ratio of his speed in still water to the speed of the stream?

Options for question 21

Show the answer and explanation
CorrectNot quiteAnswer D

Correct answer: D

Explanation

  1. Twice the time means half the speed: b+s=2(b−s)b + s = 2(b - s).

  2. So b=3sb = 3s, and b:s=3:1b : s = 3 : 1.

Worth noting

2:12 : 1 is the ratio of the downstream and upstream speeds, not of boat to stream.

Concept
Speeds from the ratio of times
Typical time
120 s
Your time
—
The rule this testsUpstream and downstream speeds
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Ten questions from Boats & Streams, Pipes & Cisterns, at your own pace.

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

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