Boats and streams: upstream = b − s, downstream = b + s

CAT has tested this idea 3 times across 3 papers, from 2017 to 2025. Solve one, and the others are the same method with different numbers or wording, which is why repeated concepts are the most efficient thing to practise.

Question	What it asks	Answer
CAT 2025 Slot 2 · QA Q19	48 min more upstream; second rower's round trip	8
CAT 2023 Slot 3 · QA Q13	2 h down, 3 h up; second boat's round trip 6 h	A
CAT 2017 Slot 1 · QA Q7	doubling boat speed cuts round trip by 75%	B

Part of Time, Speed & Distance (48 questions since 2017).