Determine departure time from travel times
Overview
This question evaluates a candidate's understanding of relative motion, time-distance-rate relationships, algebraic modeling, and quantitative reasoning. Commonly asked in technical interviews for Statistics & Math and Data Scientist roles, it assesses the practical application of setting up and manipulating equations from multi-step word problems rather than purely conceptual theory.
SIG (Susquehanna)
Aug 11, 2025, 12:00 AM
Data Scientist
Take-home Project
Statistics & Math
0
0
Canoe and River Current Timing
Context
Two friends paddle on a river with a constant current of 2 mph. Their paddling speed relative to the water is constant and the same on both days.
- Day 1: Starting at their original launch point, they canoe upstream for 4 hours, then immediately turn and paddle downstream for 5 hours.
- Day 2: From where they ended Day 1, they paddle upstream back to the original launch point, which is 23 miles upstream from their Day 2 starting location. They arrive at 16:00.
Task
At what time did they depart on the return trip (i.e., the Day 2 upstream trip back to the original launch point)?
Solution
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