# Interview Question: One hundred tigers and one sheep are put on a magic island that only has grass. Will the sheep be eaten?

**The facts of the question:** There are one hundred tigers and one sheep are put on a magic island that only has grass. Tigers can eat grass, but they would rather eat sheep.

- Each time only one tiger can eat one sheep, and that tiger itself will become a sheep after it eats the sheep.
- All tigers are smart and perfectly rational and they want to survive.

**So will the sheep be eaten?**

## Strategy and Approach to Answering a Problem Solving Interview Question

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 Interview Question

This problem solving interview question is a classic example of game theory. In thinking this out, let’s start with a simplified version of the problem by reducing the number of tigers.

So let’s start with a simplified version of the problem. If there is only 1 tiger ( n=1), surely it will eat the sheep since it does not need to worry about being eaten. How about 2 tigers? Since both tigers are perfectly rational, either tiger probably would do some thinking as to what will happen if it eats the sheep. Either tiger is probably thinking: if I eat the sheep, I will become a sheep; and then I will be eaten by the other tiger. So to guarantee the highest likelihood of survival, neither tiger will eat the sheep. If there are 3 tigers, the sheep will be eaten since each tiger will realize that once it changes to a sheep, there will be 2 tigers left and it will not be eaten. So the first tiger that thinks this through will eat the sheep. If there are 4 tigers, each tiger will understand that if it eats the sheep, it will turn to a sheep. Since there are 3 other tigers, it will be

eaten. So to guarantee the highest likelihood of survival, no tiger will eat the sheep.

Following the same logic, we can naturally show that if the number of tigers is even, the sheep will not be eaten. If the number is odd, the sheep will be eaten. For the case

n=100, the sheep will not be eaten.

**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., Microsoft, Google, Goldman Sachs)

- 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
- Card Game Interview Question
- Crossing the River Interview Question
- Dog Show Interview Question
- Equal Halves of Rectangular Birthday Cake Interview Question
- Estimate the market demand in gallons for skim milk consumed in the U.S. in a given year.
- How many golf balls can you fit in a school bus?
- How many street lamps are there in Manhattan?
- How many times a day does a clock’s hands overlap?
- How Many Zeros in 100 Factorial (100!)?
- How much would you charge to wash all the windows in New York City?
- In a country, in which every family wants a boy
- Rising Tide Interview Question
- The Fermi Problem – How many Piano Tuners are there in Chicago?
- The Heaviest Ball Interview Question
- The Monty Hall Interview Question
- The Race Interview Question
- Tiger and Sheep Interview Question
- Why are manhole covers round?