Rule substitution questions are often the most intimidating question type for students new to logic games. These questions come at the end of the game, when time pressure is most acute, and their phrasing can be confusing. However, with the right strategy, rule substitution questions can be very manageable.
You know that you are dealing with a rule substitution question when you see language like: “Which one of the following, if substituted for [rule], would have the same effect on [the arrangement of variables in the game]?” If we were solving a logic game that asked you to match 6 musicians with 6 instruments, the rule substitution question might read: “Which one of the following, if substituted for the condition that no woman plays the violin, would have the same effect in determining the assignment of instruments?”
Note that rule substitution questions ask three things of the test-taker:
- To focus on one of the existing rules of the game.
- To pretend that rule was removed from the game.
- To find a different rule that would have the same impact on the game as the eliminated rule.
You want the new rule to create the same constraints or conditions that the old rule created – no more and no fewer. In other words, using this new rule in place of the old one would not change the game’s outcomes or set-up.
So, how should you approach a rule substitution question?
Step 1: Identify the original rule’s impact.
Before you even look at the answer choices, consider how the original rule impacted the game. What restrictions did it create? When did it affect the arrangement of the variables? Take a few notes about how the original rule affected the game, paying attention to the following aspects:
- Rules limit how variables can be arranged or place conditions on the game’s process. What basic restrictions or conditions must the new rule place in order to align with the old rule?
- Consider the limits of the rule – how far does the rule go and what does it not do? Keep in mind that an answer choice is wrong if it creates new conditions that the original rule did not create.
- Consider how the eliminated rule interacted with other rules in the game. The new rule must interact with the other rules in exactly the same way as the eliminated rule.
Step 2: Eliminate based on conditions, limits, and interaction.
Next, look through the answer choices. Eliminate answers that do not match the impact of the original rule, considering the conditions, limits, and interactions.
Step 3 (Optional): Test your answer.
Many times, you will be able to identify the correct answer through elimination. Occasionally, you will be torn between choices. To check answer options more thoroughly, you can use these tests:
A) Go through the other existing rules individually. Double-check that the rule you selected interacts with each of the other rules in the same way as the original rule. Are any new conditions created? Are any needed conditions missing?
B) Try plugging it in. Test out a few scenarios and see if the game comes out the same way for both the old and new rule. Try creating a new diagram using the new rule. Does it look the same?
C) Go back to some of the other questions in the game that you answered earlier (but make sure they are questions that only used the original rules of the game and did not introduce any new information). Try the questions again using your new rule in place of the old rule. Do you get the same answer that you did before?
- Remember that the answer choice that sounds most similar to the original rule is not necessarily correct. Instead, focus on the impact that each choice would have on the arrangement of variables in the game.
- These questions come at the end of the game – that’s actually a huge advantage. You already know a lot about this rule and can use that knowledge to help you solve this problem.
- Don’t stress too much – you got this!