Planning Ahead
Logic
Level
1
Douglas has a weird habit: he tells the truth on every day but Saturday and Sunday, on which he always lies.
Which of the following days couldn't he say "I will lie tomorrow."?
Friday
Saturday
Sunday
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1 solution
Relevant wiki: Truth-Tellers and Liars
On Friday he can say that because on Fridays he tells the truth and on Saturdays he lies.
On Saturday he cannot say that because he lies both on Saturdays and on Sundays.
On Sunday he can say that because on Sundays he lies and on Mondays he tells the truth.
Hence, the solution is Saturday .