LSAT Analytical Reasoning Basic Grouping Game Explanation

Basic Grouping Game

The following is a free explanation of a basic Grouping Game. This game can be found as the second game in the LSAT Analytical Reasoning Section 1 from the June 2007 exam.

STOP Before you read this get your self a copy of the June 2007 LSAT and do the Analytical Reasoning section. (Free Copy of June 2007 LSAT Here) Then come here for the explanation of how to do the games. Book mark this page and come back when you have completed the June 2007 games section. Click here for some tips on making the most of your practice LSATs.

OKAY – so you have completed the Analytical Reasoning section of the June 2007 LSAT on your own. Now here is a full set of explanations for you to practice from.

Let’s go on to the second game. Each game consists of an introductory paragraph, a set of rules and then a series of questions. As you read the introductory paragraph and set of rules you MUST summarize them all into a simple diagram and if necessary a few short hand rules on the side. We suggest a short hand for you to use here or you can develop your own, just make sure it is neat and easy to understand.

IMPORTANT – when you have completed summarizing the game and rules you must have included everything. You should not have to return to the rules or the introductory paragraph at any time when you are doing the questions. Your diagram and shorthand rules should give you all the information you need. If you find yourself returning to the game description you need to work on your diagram and shorthand rules notations.

Now let’s look at the introductory paragraph which describes the basic set up of the game. In this game we are selecting from three types of entities and placing them into three groups. The entities to select from are the films G, H and L and the groups are Thursday, Friday and Saturday. This is called a basic grouping game. Later you will learn more about grouping games in our grouping game tutorial. Note that to save time you should express entities and groups in shorthand with just one or two letters to represent each. So we have G, H and L instead of Greed, Harvest and Limelight.

By summarizing the introductory paragraph we get the following start to our diagram:

G H L
at least once each
max once per day

Th Fr Sa
___ ___ ___

GAME DIAGRAM TECHNIQUE – whenever a minimum or maximum number of entities for a group is given you can express the minimum with solid underlines representing that you must fill that many spots and the maximum with dotted underlines representing that you may or may not fill up to that many spots.
Here we know the minimum is one movie per day and we do not yet know the maximum.

Now we can move on and add our rules to the diagram or express them in shorthand.

Rule 1: Tells us that we definitely have H on Thursday and that no film is shown after it. Add this to our diagram as follows:

G H L
at least once each
max once per day

Th Fr Sa
___ ___ ___
H-x

Rule 2: Tells us that we must have either G or L but not both on Friday and nothing will follow either G or L. Add this to our diagram:

G H L
at least once each
max once per day

Th Fr Sa
___ ___ ___
H-x G/L-x

Rule 3: Tells us that we must have either G or H but not both on Saturday and nothing will follow either G or H. Add this to our diagram:

G H L
at least once each
max once per day

Th Fr Sa
___ ___ ___
H-x G/L-x G/H-x

Now we have a complete diagram with all the rules and information represented. Let’s move on to the questions.

Question 1:

Most games in the LSAT will start with a “complete and accurate” question like this one. While most questions in the games section should be answered by testing out each answer choice we find there is a more efficient method for the “complete and accurate” question type. Simply take each rule in turn and apply it to each answer choice to see if it violates the rule. As an answer choice violates a rule cross it off and move on.

Using this technique take Rule 1 and apply it to each answer choice. Answer choice (D) violates Rule 1 as we have a film showing after H. Cross off (D) and move on to Rule 2.
(B) violates Rule 2 as it has both G and L. Also (E) violates Rule 2 as H follows L. We are left with only (A) and (C). Apply Rule 3 to (A) and (C). Neither of these answer choices violate Rule 3. Now check the other rules of the game that we must have at least one of each film but each film can be shown only once per day. Answer choice (A) has no G film. We are left with only (C), the correct answer choice.

Remember this question type is almost always the first question of a game, and this technique of applying each rule in turn can save lots of time. If you find you cannot cross off all but one answer choice you are missing a rule or miss applying a rule.

Question 7:

This is a CANNOT be true question. In a Cannot be true question we will try to show that each answer choice can be true. If it can be true cross it off and move on. To see if it can be true re-draw your diagram and plug in the information from your answer choice, then fill in the rest of the entities without violating any rules. If this cannot be done then it cannot be true and so you have your correct answer.

(A)
First re-draw your master diagram for each question.

Th Fr Sa
___ ___ ___
H-x G/L-x G/H-x

For (A) try to put H as the last film shown on each day.

Th Fr Sa
L
H

We can make H the last film shown on Thursday and Saturday but not on Friday because either G or L must be last on Friday, from Rule 2. H cannot be last on each day so (A) cannot be true (A) is the correct answer. You can move on to the next question but here we provide an explanation of why each other answer choice is wrong.

(B) L can be shown on each day of the festival in the following combination without violating any rules:

Th Fr Sa
L L L
H G

(C) G can be shown second on each day of the festival with the following combination without violating any rules:

Th Fr Sa
L H L
G G G
H

(D) A different film can be shown first on each day as follows:

Th Fr Sa
H L G

(E) A different film can be shown last on each day as follows:

Th Fr Sa
H L G

As each answer choice other than (A) can be true and only (A) cannot be true then (A) is your correct answer.

Question 8:

This question asks for a maximum number of showings or a maximum number of entities that will fit in the diagram. In this type of question you want to try to put as many entities in the diagram without violating any rules. This will give you your maximum. This question provides us with some additional information “L is never shown after G is shown” so start by plugging this into your master diagram and then try to fit as many entities or films into your diagram without violating any rules.

Re-draw your master diagram:
Th Fr Sa
___ ___ ___
H-x G/L-x G/H-x

Using your extra information and try to fit the maximum number of entities into the diagram. Given that our extra information is that once G is shown we cannot use L again we should probably try to leave G to later or as late as possible in the diagram. That way we can use L in each day, maximizing the number of entities.

Th Fr Sa
L H L
H L G

This is the maximum number of entities or films we can fit into the festival if we are told that once G occurs then L can not occur again. If we try to put G sooner in the festival then we will not have as many films shown. So (D) is our correct answer.

Question 9:

This question tells us that we must use the following set of entities to fill our diagram:

GGG
HH
L

It is a Must be True question so we will plug in our information above and then test answer choice to see if it can be false, if an answer choice can be false we can cross it off an move on.

Try plugging in the required set of entities. We come up with only two options that do not violate the rules.

Option 1:
Th Fr Sa
G H L
H G G

Option 2:
Th Fr Sa
L H G
G G
H

Given that these are our only two options that satisfy our diagram and extra information then we can simply look at each answer choice to see which one must be true.

(A) Is not necessarily true as we can see in option 1.
(B) Is not necessarily true as we can see in option 2.
(C) Is not necessarily true as we can see in option 1.
(D) Is not necessarily true as we can see in option 1.
(E) Must be true because G must be shown 3 times and so must be on every day and H must be shown twice and must be shown on Thursday and Friday because if H is shown on Saturday then we cannot have G on Saturday from Rule 3. So H must be on Thursday and Friday. So H and G must be on Thursday and Friday. (E) is the correct answer.

If you did not come up with the two options shown above you can also test each answer choice as you would in most must be true questions by trying to show that the answer choice need not be true. If it need not be true you can cross it off and move on to the next answer choice until you find the one that must be true.

Question 10:

This question tells us that we must use the following set of entities to fill our diagram:

LLL
HH
G

We are then asked to find the complete and accurate list of films that could be the first film on Thursday. This means that any film that could appear first on Thursday must be included in the list. For this question rather than testing each answer choice simply test each of the three films to see which can be shown first on Thursday.

Re-draw the master diagram:
Th Fr Sa
___ ___ ___
H-x G/L-x G/H-x

Can H be shown first on Thursday?

Th Fr Sa
H

If we put H first on Thursday we know from our diagram that no other films can follow H on Thursday. We must include three Ls in this question and we cannot have L appear more than once on one day. L needs to appear on each day. Therefore H cannot appear first on Thursday.

Should we test G or L next? If you look at the answer choices you will see that by taking away all that include H we are left with only (B) L or (D) G & L. Since both (B) & (D) include L we do not need to test L. Just test G.

Can G be shown first on Thursday?

Th Fr Sa
G
Remember that L must appear three times or once on each day.

Th Fr Sa
G L L
L

And we must include two Gs.

Th Fr Sa
G L L
L H
H

All of our rules are satisfied and we have G, LLL, and HH as required for question 10. So G can appear first on Thursday and our correct answer choice is (D).

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