Earlier today I set you the following Puzzle, from Raymond Smullyan’s What is the name of this book?
Beautiful Portia has three caskets: one gold, one silver and one lead. Inside one of them is her portrait. Her father’s will has determined that any suitor must choose the casket with the portrait in order to win her hand in marriage.
1) Portia has the following words written on the caskets:
Portia tells her suitor that of these three statements at most one is true. Which should he choose?
2) Portia has these words written on the caskets:
She tells her suitor that at least one statement is true and at least one is false. Which one should he choose?
Solutions
1) The potrait is in the silver casket.
The gold and lead caskets have statements that are opposites, which means that exactly one of them must be true. So the statement on the silver casket must be false, which means that it contains the portrait.
2) The portrait is in the gold casket
If the portrait is in the lead casket, then all three statements are true. If the portrait is the in silver casket, then all statements are false. So the portrait must be in the gold casket, in which case two statements (gold, silver) are true and one (lead) is false.
I set a puzzle here every two weeks on a Monday. If you want me to send you an email each time I post a new puzzle, send me your email.
I’m always on the look-out for great puzzles. If you would like to suggest one, email me.
My most recent book is Can You Solve My Problems, A Casebook of Ingenious, Perplexing and Totally Satisfying Puzzles. My children’s book Football School: Where Football Explains The World, co-written with Ben Lyttleton, was recently shortlisted for the Blue Peter Book Award 2017.
View all comments >