#15 - Local, Must Be True, Maximum

[Dave Killoran]

Complete Question Explanation
(The complete setup for this game can be found here: lsat/viewtopic.php?t=6469)

The correct answer choice is (D)

In this question you are asked to find the maximum number of friends that can appear in a photograph when Y does not appear in the photograph. This requires two steps: first you must establish what must be true and what cannot be true when Y does not appear, and second you must then arrange the other variables in a way that allows for the most number of friends to appear in the picture. Let’s examine both steps:


Step 1: From the third rule, when Y does not appear in a photograph, then R must appear in that photograph:


Y R


From the fourth rule, when R appears in a photograph, then W cannot appear in that photograph:


R W


Via the contrapositive of the first and second rules, when W does not appear in a photograph, then S and U cannot appear in that photograph:


W S U



Thus, when Y does not appear in a photograph, then R must appear in the photograph, and W, S, and U cannot appear in the photograph.


Step 2: The remaining two variables that have not yet been addressed are T and Z. Because Z is a random, Z can automatically be included in the photograph. So, the final question is whether T is compatible with R, and the answer is yes. Although R and T both figure in the fourth rule, that rule individually relates R and T to W, and it does not make a direct connection between R and T. Thus, R and T can appear in a photograph together, and the maximum number of friends that can appear is three—R, T, and Z. Answer choice (D) is correct.


Answer choices (A), (B), (C): Each of these answer choices is incorrect because more than three friends cannot appear in the photograph when Y does not appear.

Answer choice (D): This is the correct answer choice.

Answer choice (E): This answer choice is incorrect because the question asks for the maximum number friends who can appear in the photograph when Y does not appear, and this answer is not the maximum.