Jo announces: "I have more than 999 books."
Jean says: "No Jo! You have fewer than 1000 books."
Mary says: "Jo has at least 1 book."
Only one of these statements is true. How many books does Jo own?
Discuss the method and solution used.
The only person who can be telling part of the truth is Mary because regardless of how many books Jo has, 999 or 1000, he in the very least has one book. So Mary is ...
A logical thinking question is posed.