the Bell cell phone, Brian got the Sprint cell phone, and Joelle got
the AT&T cell phone.
Dan didn't get the AT&T, so he could have gotten the Sprint or
But someone else
got the Sprint, so Dan had to get the Bell.
know that it was Brian who got the Sprint, because he is the only man
in the group besides Dan.
So that leaves
Joelle with the AT&T.
The conclusion is
correct, but the logic is completely wrong.
When Dan says he didn't
order from AT&T then we know that he didn't.
When Brian says that he
thought Dan ordered from AT&T then we know that Brian didn't order
from AT&T either (assuming he knows that there was only one
Therefore Joelle ordered
the AT&T phone.
We know that Brian
ordered from Sprint because he's described as "the guy who ordered from
Sprint", and therefore Dan ordered from Bell.
However... when the
puzzle says, "That was all the man at the counter needed to know", this
Unless Brian is wearing a sign that says, "the guy who ordered from
Sprint", or maybe a baseball cap with a Sprint logo, the man at the
counter has absolutely no way to know whether Dan or Brian ordered a
The puzzle is broken as
is, but could be fixed by changing the line that says:
The guy who ordered from
Sprint says: "Oh, I thought you did".to
The guy wearing an "I
hate Bell" t-shirt says: "Oh, I thought you did".
In the modified puzzle,
we can see that Brian didn't order from AT&T (unless he doesn't
know only one AT&T phone was ordered), and that he would never
order from Bell.