Mollie must be assigned to 1922 if which one of the following is true?

Claire on May 29, 2019


I really struggled with this game. How does Yoshio being assigned to 1921 ensure that Mollie is in 1922? The two don't seem to be related. thanks!

1 Reply

Ravi on May 30, 2019


Great question. Let's look at the setup first.

We have a 4-slot game board with 2 pieces that are out

_ _ _ _ | _ _

Our pieces are L, M, O, R, T, and Y.

Rule 1 says L or T has to be in 1923

_ _ L/T _ | _ _

Rule 2 says if M is in, she's in 1921 or 1922

M in - >21 or 22

Rule 3 says if T is in, then R is in.

T - >R

Rule 4 says if R is in, then O has to be in in the year before R

R - >OR

We can also combine rules 3 and 4 together

T - >R - >O and OR

This is an important inference because if we try to put O out, that
means both R and T would also have to go out. However, we only have 2
spots in the out group. so this means that O must go in.

If R goes out, we know that T goes out, so this is a good place to
split up the game board.

_ _ L/T _ | _ _

In this game board, we're putting R in, so OR have to go together. The
only spot for them to do so is in 1 and 2.

O R L/T _ | _ _

This also means that M is out since 1921 and 1922 are occupied by O and R.

O R L/T _ | M _

Now let's look at our other board.

_ _ L/T _ | _ R

If R is out, then T is out.

_ _ L _ | T R

Now let's look at the question. Mollie must be assigned to 1922 if
which one of the following is true?

We know M is in the game, so we're only concerned with our second board.

_ _ L _ | T R

(A) Louis is assigned to 1924.

The only scenario in which this occurs is the first board, and M is
out in that board, so this answer is automatically out.

(B) Onyx is assigned to 1921.

(B) doesn't work because in our first game board, we have O in 1921 and M out.

O R L/T _ | M _

(C) Onyx is assigned to 1924.

If O is in 1924, M could still be in 1921 or 1922 in our second game
board, so (C) is out.

(D) Tiffany is assigned to 1923.

The first game board is the only board where T could be in 1923, and
in that board, M is out, so (D) is out.

(E) Yoshio is assigned to 1921.

Our first board has O in 1921, so we're looking at the second game board.

_ _ L _ | T R

If Y is in 1921, then M has to go in 1922 because T and R have already
filled up the out group and we know that if M is in, it has to go in
1921 or 1922. Since 1921 is full, it has to be in 1922. Thus, (E) is
the correct answer.

Does this make sense? Let us know if you have any more questions!