Boat and Stream Practice Questions with Detailed Solutions – Level 3

Boat and Stream Level 3 Hard Practice: Log Float and Cap Problems

Level 3 is meant for students in the final stage of arithmetic preparation who are already comfortable with standard boat and stream problems. It covers tricky cases such as a dropped cap, a floating log, a current that changes speed and boats moving towards each other. Every question on Aptitude360 has a worked solution.

What the Level 3 boat and stream problems test

• Still-water and stream speed from two combined trips
• A cap dropped while rowing upstream and found later downstream
• Time for a log to float between two points from the boat's downstream and upstream times
• Return trips where rain or a halt changes the stream speed or the travel time
• Two boats moving towards each other from towns on the same river
• Round-trip average speed and percentage differences in upstream and downstream time
• Trips that turn back at the midpoint or include an engine failure

Advanced boat and stream formulas and rules

• Time ratio, same distance: \( \dfrac{t_{up}}{t_{down}}=\dfrac{u+v}{u-v} \)
• Log float time, with \( t_{d} \) downstream and \( t_{u} \) upstream boat times for the same distance: \( \dfrac{2t_{d}t_{u}}{t_{u}-t_{d}} \)
• Round-trip average speed: \( \dfrac{u^{2}-v^{2}}{u} \)
• Stream speed: \( v=\dfrac{D-U}{2} \)
• Boats approaching each other: closing speed \( =u_{1}+u_{2} \)

How to prepare for hard boat and stream problems

• In cap and log problems, measure motion relative to the water: the stream carries both boat and object equally, so it cancels out.
• When the stream speed changes on the way back, write a separate time term for each leg.
• Turn percentage time differences into a speed ratio first, then solve for the unknown speed.
• Check that your stream speed is less than the still-water speed, or the boat could not move upstream.

Who this hard level is for

It is best taken after the earlier levels by aspirants of bank, SSC and MBA entrance exams who want to handle unusual boat and stream problems with confidence.