A Classic Knights and Knaves problem

Logic Level 4

A classic goes as follows:

A group of Knights and Knaves work for Ye Ole Beer Shoppe. Knights always tell the truth, while Knaves always lie. When each and every one of the employees were asked two questions, they said the following answers:

"How many people work harder than you?"

At most 10 10 people work harder than I do.

"How many people get better payment than you?"

At least 100 100 people have better salaries.

The question to the reader is:

"How many employees worked at Ye Ole Beer Shoppe in total?"

Details and Assumptions \text{Details and Assumptions}
We assume the reader never lies. However, if you do choose to lie, it is to your own discretion as you will get the answer to the question wrong.

Image credit: Wikipedia Piotrus


The answer is 111.

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2 solutions

If we arrange the employees in order of how hard they work, if all of them say the same statement, then the first 11 11 people must be knights. Thus, there are 11 11 knights in all the employees. Now, if we arrange the employees in order of income, the first 100 100 people would be lying, whereas anyone after 100 100 people would be telling the truth. We know that there are 11 11 such people. Thus, the total number of employees is 111 \boxed{111}

There is an error here. Your solution assumes that no employees work equally hard or receive equal pay. What if there were a thousand knaves who were all paid equally? Then they could all say that "At least 100 people have better salaries." and still be lying because no one has a better salary. And all of the knights would still be telling the truth because 1000 is at least 100.

Natasha Honcharik - 6 years ago

i was so close!

Mayank Arora - 7 years ago

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yup me too I typed 112.

Vipul Singh - 6 years, 9 months ago

i typed 110

Vighnesh Raut - 6 years, 5 months ago

Used the same method. Only used the wellpaidness condition before to testify that there were indeed 100 knaves, and then the hardwork condition to testify that there were 11 knights. And yes, Natasha Honcharik's point dawned on my mind too. But, I rejected that idea as the question was asking for a unique answer.

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