Question

Assume that you are John Snow and you know nothing about what day it is today. Now you decide to go and ask Arya Stark and Tyrion Lannister about it. What you know is that Tyrion lies every Tuesday, Wednesday and Thursday and the other days he speaks the truth. Arya lies on Fridays, Saturdays and Sundays, and the other days of the week she speaks the truth. "Yesterday I was lying," Tyrion told you. "So was I," said Arya. What day is it?

Answer 1

Answer: Friday.  

Explanation: The only day they both tell the truth is Monday; but today can’t be Monday because Tyrion also tells the truth on Sunday (yesterday). Going day by day, the only day one of them is lying and one of them is telling the truth with those two statements is Friday.