EduFarming
Your list · 0हिं

Type at least two letters. Press Esc to close.

↑↓ navigate↵ openTAB cycle filter

Time, Speed & Distance · Question 65 of 71

Question 65

MediumOriginal question

A boat's speed in still water is 12 km/h. It takes twice as long to go a certain distance upstream as to go the same distance downstream. What is the speed of the stream?

Options for question 65

Show the answer and explanation
CorrectNot quiteAnswer B

Correct answer: B

Explanation

  1. Twice the time means half the speed: downstream speed = 2 × upstream speed.

  2. 12+s=2(12−s)12 + s = 2(12 - s), so 3s=123s = 12.

  3. s=4s = 4 km/h.

Worth noting

6 km/h simply halves 12. Check it: downstream 18 and upstream 6 is a ratio of 3, not 2.

Concept
Ratio of times upstream and downstream gives the stream speed
Typical time
60 s
Your time
—
The rule this testsBoats and streams
Practise this chapter →

Ten questions from Time, Speed & Distance, at your own pace.

Practise this chapter →

Ten questions from Time, Speed & Distance, at your own pace.

Practise this chapterAll 71 questions in Time, Speed & DistanceRevise the notes for Time, Speed & Distance