Question

When three professors are seated in a restaurant, the hostess asks them: "Does everyone want coffee?" The firstprofessor says: "I do not know." The second professor then says: "I do not know." Finally, the third professor says: "No, not everyone wants coffee." The hostess comes back and gives coffee to the professors who want it. How did she figure out who wanted coffee?

Short answer

The first and the second professor need the coffee and the third professor does not need the coffee.

Step-by-step solution

Introduction

In response to such directions, truth-tellers frequently supply more comprehensive information in order to show their innocence. Liars, on the other hand, want to keep their mistakes hidden.

Explanation

Consider the following scenario: Three professors are seated at a restaurant, and the hostess inquires, "Does everyone want coffee?" "I don't know," the first professor replies. "I don't know," answers the second professor.

"No, not everyone likes coffee," finally replies the third professor.

The hostess reappears and hands the professor his coffee. The goal is to determine who wants coffee.

If the first professor did not want coffee, he would have said so, but instead, he just says, "I don't know." As a result, the hostess and the other professors are aware that the first professor had shown an interest in coffee.

The second professor, on the other hand, expressed an interest in coffee. The hostess now knows that the third professor does not want coffee because he said no." As a result, the first professor would answer no if he didn't want coffee, but he didn't, instead saying, "I don't know." As a result, the hostess and the other professors are aware that the first professor had shown an interest in coffee. The second professor, on the other hand, expressed an interest in coffee.

The hostess now knows that the third professor does not want coffee because he said no."

As a result, the first and second professorsdesired coffee, but the thirddid not.