Cheryl's Birthday
Cheryl gives Albert only the month and Bernard only the day of her birthday, which is one of: May 15, May 16, May 19, June 17, June 18, July 14, July 16, August 14, August 15, August 17. Albert: "I don't know the birthday, but I know Bernard doesn't either." Bernard: "At first I didn't know, but now I do." Albert: "Now I know too." When is Cheryl's birthday?
Related problems & prerequisites
Worth solving first
- The Camel and the Bananas 6.0/10
Source: Adapted from the Singapore and Asian Schools Math Olympiad (SASMO) 2015, where it appeared as a competition question.