Ravi
· 2019-02-01 08:16
@Jersson-Morocho,
Great question. If you build out your hypothetical game boards well
after reading the rules, there is a very fast way you can answer this
question. But first, let's make sure we are setting up the game
properly.
We're told that there are 5 pieces (F, L, M, P, and S) in a mailbox
going to 3 different people (g, j, and r). We know that each person
receives at least 1 piece of mail, and all of the pieces of mail are
used.
g j r
_ _ _
Rule 1 says L and M can't go in g. This means that L has to go in j or
r and M also has to go in either j or r
1) L j/r
M j/r
Rule 2 says if L is in r, then P is in j
2) Lr - >Pj
/Pj - >/Lr
Rule 3 says F must be with at least one other piece of mail
3) F not solo
Now it's time to take the rules and see if we can split the game board
into multiple hypotheticals.
In looking at our rules, rules 1 and 2 appear to be great places to
split since L has to be in j or r and L is also involved in a
conditional relationship with P. Let's put L in j in one game board
and L in r in the other
g j r
_ L _
g j r
_ _ L
For the top game board, rule 2 falls away because the sufficient
condition is failed. For the bottom game board, rule 2 is triggered,
so P must go into j
g j r
_ L _
g j r
_ P L
In both game boards, M can go in either j or r. Additionally, we just
need to place F with at least one other piece in both game boards.
That leaves us with S. If we look at the bottom game board, g is still
empty and it needs at least one piece. M can't go in there since it
has to be in j or r. That means that either F or S must go in g.
However, if F goes in g, it has to come with someone else, so S must
go in there. Alternatively, if F goes somewhere else (j or r), then S
must go in g to give g at least one piece, so we know that S must be
in g no matter what in the bottom game board.
g j r
_ L _
g j r
S P L
Now we know that for the top game board, M has to go in j or r, F must
go with at least one other piece, and P and S are floaters.
For the bottom board, F and M are now both floaters.
Let's look at the question now. The question asks, "Which one of the
following CANNOT be a complete and accurate list of the pieces of mail
addressed to Jana?"
As you noted, we could test out all of the different scenarios to get
the right answer. However, the faster way to do this problem is to
look at our game boards and recognize that j must have either L or P
in it. (E) does not include either L or P, so we know that this is a
list that WOULD NOT WORK for j since j needs to have either an L or P.
Does this make sense? Let us know if you have any more questions!