#11 - Local, Justify, Rule Substitution

[Administrator]

Complete Question Explanation
(The complete setup for this game can be found here: lsat/viewtopic.php?t=11881)

The correct answer choice is (D)

This question asks you to suspend the second rule and replace it with a rule that has an identical effect. The second rule creates a minimum split block for the two Rs, so that limitation must be equalled by the correct answer. This immediately casts suspicion on an answer choice such as (C), which places just one business between the two restaurants.

Given that one of the Rs is always at the end of the row (from the first rule), what is the functional effect of the second rule? To place the other R at the other end of the row (spaces 3 and 4 in Template #1, and spaces 4 and 5 in Template #2). Thus, you need a replacement rule that keeps an R at that “opposite” end while not adding any further restrictions to R’s movement. Note that, just because the two templates when combined limit R to spaces 3, 4, and 5 does not mean answer choice (A) is correct. (A) actually allows for greater latitude for R than it currently has: R cannot currently be in space 5 in Template #1 or space 3 in Template #2. Thus, answer choice (A) cannot be correct.

To evaluate this question, consider what else you know about the other R. When it is on the other side of the row, is there any constant that appears in relation to the R? Yes, P is always at the other end of the row. Thus, look for an answer that links P and R, and determine whether that answer could possibly be correct.

Answer choice (D) is the only answer to feature P and R, and the result of this rule would be to keep the “second” R within three spaces of P at all times. This would restrict R to spaces 3 and 4 in Template #1, and spaces 4 and 5 in Template #2 (remember, O or V must always be next to P, so space 2 in Template #1 is always unavailable, and space 6 in Template #2 is unavailable). That is the identical effect as the second rule, and thus answer choice (D) is a perfect equivalent to that rule, and therefore the correct answer.

[twendell]

How is A eliminated?

[Zach Foreman]

twendell,
In order to eliminate a substitution, you must show that it allows a set up that the original doesn't or that it doesn't allow one that the original does. In other words, you need a counterexample.
A says "A restaurant must be in either space 3, space 4, or space 5.". Well, can a restaurant be in space 3 and space 1? According to the original rules, no. But we have gotten rid of that rule so we could have RTRSOVP since TV are separate, P is at one end and R at the other and P is next to V. So it doesn't violate any of the new rules but is explicitly not allowed by the original set because R is not separated from the other R by at least 2 spaces.

[deke97]

Doesn’t the language In answer choice D of “no more than two businesses” mean that there can be less than two businesses that separate P and R? Additionally can’t the closest R be more than 2 businesses away from P? I chose D because it was the best choice out of the options but I wasn’t fully sure about it.

[Jeremy Press]

Hi deke,

Yes, that's what the language means: the language of answer choice D permits there to be less than two businesses that separate P from the nearest R. But that's consistent with the original rule we're subbing for. Under that original rule (in conjunction with the other rules) the restaurant not at the end of the line would have to be at most separated from P by two other businesses. And that restaurant could be separated from P by fewer businesses, so long as there were at least two businesses (maybe more!) separating it from the other R (the one at the end of the line).

So, for example, this arrangement for the P and the R's would be fine under both the original conditions and the new condition in answer choice D:

P ___ R ___ ___ ___ R (that's only one business separating the P and the closest R)

But, under the original rules, the closest R cannot have more than two businesses separating it from P, because that would put it too close to remaining R. See the following solution:

P ___ ___ ___ R ___ R (that's only one business separating the R's)

If, under the original rules, three businesses separate the closest R from P, then the closest R is too close to the remaining R to be consistent with the original rule that at least two other businesses separate the two restaurants.

I hope this helps!

[sblack1998]

This is my setup:

P O/V R __ __ __R
P O/V __ R __ __ R
R __ __ R __ O/V P
R __ __ __ R O/V P

As you can see from my set-up a Restaurant had to be in either space 3, 4 or 5. So, based on my setup, A and D made sense to me. I guessed A and got it wrong obviously. What should I have done differently.

[KelseyWoods]

Hi sblack1998!

With a Rule Substitution question like this one, we're not just looking for an answer choice that describes something that must be true. We need an answer choice that could replace the specified rule giving us all the same restrictions we originally had but without adding any new ones.

Neither (A) nor (D) add any new restrictions. But answer choice (A) does not retain all of the restrictions of our original rule.

Answer choice (A) describes something that must be true according to our original diagram. But it doesn't actually limit the restaurants in the same way. If we replace the rule that the two restaurants must be separated by at least two other businesses with the rule that just states that a restaurant must be in either space 3, space 4, or space 5, then couldn't we have a restaurant be 1st and 3rd? Orr 5th and 7th? That replacement allows the restaurants to have fewer than two other businesses between them so it doesn't retain all of the same restrictions as our original rule.

Answer choice (D) ensures that we would have all of the same restrictions as we had with our original rule. If we can't have more than two businesses between the pharmacy and the restaurant closest to it, then there's no way to have fewer than two businesses between the two restaurants. This rule retains all of the same restrictions as our original rule without adding new restrictions, and thus, it is correct.

Hope this helps!

Best,
Kelsey