A boat travels a distance of 20 km in 2.5 hours when moving downstream and in 5 hours when going upstream. What is the speed of the boat in still water?

Answer Choices

Correct answer marked below

2 km/hr

4 km/hr

6 km/hr

Correct

8 km/hr

10 km/hr

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Explanation

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Official Explanation

Official

Let V be the speed of the boat and x be the speed of the stream. To find the speed of the boat in still water, we set up the equations: (V + x) * 2.5 = 20 and (V - x) * 5 = 20. From the first…

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Comments

JakeNov 16, 2024

This is definitely a test-day trap

MuhammadJan 10, 2025

thank you very much!

What this question tests

What it tests

Your application of distance = rate × time to trains, boats, and commuters, including relative speed.

Common trap

Mixing units (miles per hour vs. minutes) or averaging speeds — average speed is total distance over total time.