I have five close friends, Andrew, Benjamin, Cassie, Danielle and Eric. I know that one of them has a birthday today but I can't remember which.
I asked Andrew who had a birthday today, and he responded:
It's not my birthday today, but between me, Benjamin and Cassie exactly one of us is lying.
"Okay then." was my response.
I thought, "What exactly is that supposed to tell me?". I decided to go ahead and ask Benjamin whose birthday it was today. I wasn't too surprised when he replied:
It isn't my birthday today either. I am lying, or Cassie is lying or Danielle is lying, but only one of us is lying.
"But how am I supposed to know if you are telling the truth?" I asked. There was no response.
so I decided to ask Cassie instead, hoping for a more helpful response but expecting the worst. She told me this:
Out of all of us there are at least three liars
"Gee, thanks for that." I sarcastically responded. I was getting sick of this little game that my 'friends' were playing on me.
I had no choice, in order to find out whose birthday it was, I would have to get as much information as I could. This is what Danielle told me:
It is my birthday today!
At this point, I could not be sure, so I stuck with my plan and asked Eric what he thought. This is what he said:
What Cassie says is true.
I think that with that information, I should be able to figure out whose birthday it is, but I need you guys to help me out, so I can be sure. I am certain that if one of my friends lies, everything they say is false.