LG Game 2 Question 11 Explanation, by LSATHacks
Rule substitution questions seem hard, but what you must remember is that there aren’t that many ways to achieve an effect. To do this type of question, you should figure out the full effects of the rule. We’re trying to replace the rule that “The necklace and the jar are both older than the tureen”.
But, by looking at the main diagram, we can see that there are other effects. Here is the main diagram again:
So it’s not just N and J that must be before H; it’s also F.
What about the others? Both H and P could either be before or after T.
So, look for an answer that shows awareness of these facts. D is CORRECT. It says that only H and P could go after T. That therefore forces J and N before T, even without the rule.
All of the wrong answers are wrong because they:
- Forbid things that should be allowed, or
- Allow things that should be forbidden.
The substituted rules must create scenarios that obey all other rules. This is a helpful thing to keep in mind in order to eliminate wrong answers.
- A: This contradicts the rules. T is supposed be after F.
- B: This doesn’t mention the jar, so this rule allows J to come after H.
- C: This rule allows both J and N to go after T!
- E: This says nothing about where J and N are placed. So they could both go after T.
So, A forbids something that should be allowed, and B, C and E allow things that should be forbidden.
The “if and only if” rules are especially poor candidates. You generally can’t replace an ordering rule with an “if and only if” rule.
I don’t understand how the answer is not C. It’s reads almost exactly like the rule we are replacing: N and J are both older than T; and C reads:N is older than T only if J is, am I misunderstanding something here? How does this rule allow J and N to go after T if the answer is saying they are older than T?
Well, we need N to *always* be older than T. But C restricts when that can happen. Doc if J isn’t older than T, then neither is N!
Adding a necessary condition always reduced the odds of something happening. Like if I say “You will get to work only if you take your car”. That doesn’t help you get to work, instead it restricts your options. Normally you could take a taxi, bus, etc. Now, you can’t. And it doesn’t say you can take the car: your car could break etc
“So it’s not just N and J that must be before H; it’s also F.”
I beg to differ. If we look at the diagram, F must be before H, but we cannot say the same for N and J, there are other possibilities
Question: I understand your explanation, but aren’t the substitute rules also supposed to keep previous possibilities in tact? The answer to Question 6 is A, and it states a possible order from oldest to most recent is Figurine, Headdress, Jar, Necklace, Plaque, and Tureen. If D is correct for Question 11, doesn’t that mean the Headdress and the Plaque are more recent than the Tureen, since no two items can be the same age? So then the possibility established in Question 6 is invalidated because you couldn’t have the Tureen be last.
Does my question make sense? I’m just confused how the answer to Question 11 doesn’t invalidate the answer to Question 6.
Hi! I think A does not contradict the F – T rule, because it says T is not older than F and the older one comes before the other. But it contradicts relationship b/w T and H in that T could be before or after H.
Yes, that’s correct! Thanks for catching this.
This answer choice is incorrect because it establishes a relationship between T and H that isn’t present in the original set-up.
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