Boats and streams questions with answers

Boats and streams questions are speed-distance-time with one extra number. Downstream speed is boat plus current, upstream is boat minus current, and every question in the family is built from that pair. Each walkthrough below writes both speeds out first, which turns the harder round-trip questions into simple substitution.

How to use this set

The 15 questions below are ordered the way an exam block is rather than easiest-first: two gentle openers, then a run of medium, and a hard one every sixth question — 2 of the 15 sit in the hard band. Every question is a boats & streams.

Work each question on paper before you open its solution. The walkthrough is the method itself, step for step, so reading it first turns a practice set into a reading exercise and teaches nothing. If you are stuck on the method rather than on one question, the method guide is a better place to start than the next question: Boats and streams: two speeds, one method.

15 boats and streams questions with answers

Every question below was generated by the same engine that mints the ComputePrep daily timed drill, and machine-checked before it reached this page — a multiple-choice question validates its own answer against its own options at generation, and ships only with a walkthrough attached. The walkthrough is the engine's own.

Where these questions come from

Most free practice for this topic is a scanned upload or a blog quiz, and neither can tell you a question has exactly one answer. That is the one thing this set can promise: it is minted, not typed. The engine behind it serves ComputePrep's daily timed drill, so the questions here are the same shape as the ones a live round would give you — and there is an unlimited supply of them, which is why this page can be regenerated rather than padded.

If you want the method rather than more questions, Boats and streams: two speeds, one method covers the approach, the traps and a worked table. This page and that one deliberately answer different questions: that one is how do I solve these, this one is give me boats and streams questions with the answers.

FAQ

How do I get boat and stream speed from the two given speeds?

Boat speed in still water is half the sum of the downstream and upstream speeds; stream speed is half their difference. Those two lines answer a large share of the family directly, and they are worth writing down the moment the question gives you both directions.

Why is the average speed of a round trip not the mean?

Because the upstream leg takes longer than the downstream one for the same distance. The correct figure is the harmonic mean, 2ab/(a + b) with a and b the two speeds — and the arithmetic mean will be sitting among the options.

Do escalator and aeroplane questions use the same method?

Yes. A walker on a moving escalator, or a plane with a tailwind, is the same two-speed structure with different words. Recognising the shape means one method covers what looks like three separate question types.

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