Interview Question: Crossing the River
Mr. Wong and his children, Amy and Mary, want to cross from the east side of the river to the west side in a canoe. The canoe can hold no more than 200 pounds. Mr. Wong weighs 160 pounds, and Amy and Mary weighs 100 pounds each.
How can all three of them reach the other side of the river in the canoe?
Strategy and Approach to Answering a Problem Solving Interview Question used by Top Firms (e.g., Google, Microsoft, etc.)
If you get asked a problem solving question in an interview, remember that they are NOT looking for the RIGHT answer. They are evaluating the approach you use to think out and solve the problem. A strong candidate demonstrates the following:
- Evaluates and understand the scope of the problem
- Communicates assumptions
- Demonstrates quantitative analytical skills
- Answers the question that has been asked. You’d be surprised how many candidates get lost in the analysis and solve for a different question than what was asked.
How to answer this problem solving question
In evaluating the question, there is nothing in the question that states that there it is one trip or multiple trips. Therefore if you are unsure, you can always ask the interview to get more facts or assumptions.
- First, the children paddle to the west side of the river. (200 lbs)
- Amy stays on the west side, and Mary comes back. (100 lbs)
- Then Mr. Wong rows alone to the west side, leaving Mary on the east side. (160 lbs)
- Finally, Amy comes back for Mary. (100 lbs)
- Together, they paddle to the west side of the river. (200 lbs)
Note: For this problem solving job interview question, there is an actual logical answer, however the interviewer will want to evaluate your thinking process. In answering the interview question, the lead up to your answer will be just as important as the actual answer itself.
For more problem solving, brain teasers, riddles, puzzles, logic job interview questions, please check our out Problem Solving Interview Section.
List of Problem Solving Interview Questions used by Top Firms (e.g., Google, Amazon, etc.)
- 100 Prisoners and a Light Bulb Interview Question
- 5 Pirates and 100 Gold Coins Interview Question
- Birthday Problem Interview Question
- Bridge Crossing Interview Question
- Burning Rope Interview Question
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- Crossing the River Interview Question
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