Question 23
After an adventure with his friends, the hundred-year-old Alan returns home at night. He has fitted two locks to his room. In the darkness he cannot tell which of ten identical-looking keys belong to the room. What is the smallest number of key trials that guarantees finding the required keys?
Editorial interpretation: Each lock has exactly one matching key among the ten; the two matching keys are distinct. Count trials until both keys are identified, allowing the last candidate to be inferred.
Editorial interpretation: Each lock has exactly one matching key among the ten; the two matching keys are distinct. Count trials until both keys are identified, allowing the last candidate to be inferred.