Alex came across 5 islanders, all of whom knew one another and would only answer yes-or-no questions.
What is the minimum number of questions Alex needs to ask, to successfully determine how many of the islanders are paladins?
Answer
Alex would need to ask a minimum of 3 questions.
Q1: Are there more than 2 paladins?
If the answer is no, then there are 0-2 paladins. If the answer is yes, then there are 3-5 paladins.
Once the range is known, Alex will need to ask 2 more questions in the form of, “Are there X paladins?”.
For example, is the answer to Q1 is yes, then Alex will ask,”Are there 3 paladins?” and “Are there 4 paladins?”. If the answer to both of the questions are no, then we know that there are 5 paladins.