Eating out.?

Question

When Adam, Brian and Charlie eat out, each orders either ham or pork (OK they don't get out much but please bear with me)!

1) If Adam orders ham, Brian orders pork.
2) Either Adam or Charlie order ham, but not both.
3) Brian and Charlie do not both order pork.

Who could have ordered ham yesterday, pork today?

Answer 1

Mommy is right.

Consider the following table which lists the eight possible ways for the three guys to select their meal

Adam Brian Charley
1 ham ham ham
2 ham ham pork
3 ham pork ham
4 ham pork pork
5 pork ham ham
6 pork ham pork
7 pork pork ham
8 pork pork pork

The first condition eliminates 1 and 2
The second condition eliminates 3, 6, and 8.
The third condition eliminates 4.

So there are only two "allowed" meals,
Pork Ham Ham and Pork Pork Ham.
Brian is the only one who can have ham one day and pork the next,

Answer 2

If Adam orders ham, then Brian gets pork and Charlie gets ham. If Brian orders ham then Charlie gets ham and Adam gets pork. If Charlie orders ham then Adam gets pork and Brian gets pork. Finally on day two if Adam orders pork then Brian gets pork and Charlie must have ham. So if Adam has ham yesterday, he can have pork the next. If Brian has ham yesterday, he also can have pork today. Therefore Charlie can not have both.

Answer 3

Looks pretty easy.

Adam always has to order pork because if he orders ham, it leads to a contradiction.
Adam orders ham ==> Brian orders pork ==> Charlie orders ham ==><== contradicts with assumption number two.

Seems like there are multiple solution possible.
I would say that either Charlie or Brian can order ham yesterday, pork today but not both. So either one would be the answer.

Answer 4

Charlie had to order ham yesterday, since Adam ordering ham would force the other two to order pork, which is not allowed.

Adam and Brian would have to order pork for the same reason as charlie ordering ham. It is the only possible combination.

Answer 5

If Adam orders Pork, Brian could order ham and Charlie could order Pork.

Or, if Adam orders ham, Brian and Charlie both get ham.

Answer 6

Adam could not have ordered ham because that forces Brian to order pork and Charlie to order pork (whick breaks rule 3).
That means Adam orders pork.
By rule 2, Charlie must order ham.
Brian could order either ham or pork. It doesn't matter.
Who could have ordered ham? Charlie or Brian
Who could have pork? Adam or Brian.
Charlie must order ham.
Adam must order pork.
Brian can order either one.

Answer 7

Starting with the premise Adam orders ham (A=H)
A=H -> B=P
A=H -> C=P since neither order ham
But if A=H, B=P and C=P, which contradicts the third premise.
By RAA, Adam orders pork (A=P)
Checking that logic:
A=P -> C=H
The first premise is true because the hypothesis is false.
The third is also true for the same reason.
Thus, what we can say about the situation:

Adam orders pork and Charlie orders ham. Brian can order either.

Answer 8

Adam orders pork yesterday and today.
Charlie orders ham yesterday and today.
Brian orders either ham or pork on both days.

Answer 9

Assume it was adam. see what others can order if Adam orders ham; same if Adam orders pork.

Tepeat for other two guys.

Answer 10

Any of them could have ordered either yesterday and the same or different today... it was not specified that the choices need to change day by day.


Ah, but you are correct, Adam must always order Pork... I stand corrected!