# Which one of the following, if substituted for the condition that Gold cannot be shown in any week in which Ping is s...

Alexander on February 9, 2020

Why not C?

Irina on February 19, 2020

@Alexander-Blankers,

One of the ways to approach substitution questions is to look at the effect of the original rule first. The question asks us which rule would have the same effect as the condition that G cannot be shown in any week in which P is shown?

O: G H I
W: P R S
1-1-1-1-2-2

P-> ~G
S -> H
~I 1- > H 3, 4
H 1,2 -> I 1

S !=1
H !=1

Since P & G cannot be shown in the same week, P must be paired either with I or H. And G must be paired with R because S can only be paired with H and G cannot be paired with G, thus R is the only watercolor painting that can be exhibited with G - G- >R.

Let's look at (C) If P is not shown in the first week, then S must be shown no earlier than the third week. This rule is different from the original because it presupposes that P must be paired with I, which is not the case. P cannot be paired with G, but it can be paired with I OR H. For example, this would be a valid scenario:

O I H G H
W R S R P

Here P is not shown in the first week, and S & H are shown in the second week because I is shown in the first week.

Let me know if this makes sense and if you have any other questions.