LSAT Logic Games : Solving grouping games
Study concepts, example questions & explanations for LSAT Logic Games
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Example Questions
Example Question #61 : Grouping Games
For an upcoming film festival, a panel will be formed consisting of five well-known movie critics from New York, Chicago, and Hollywood. The possible movie critics to be solicited for the panel are as follows: from New York—Frank, Grayson, and Helen; from Chicago—Katie, Larry, and Michelle; and from Hollywood—Pat, Quentin, and Roxie. Selection on the panel is governed by the following conditions:
The panel must include at least one critic from each of the three cities.
If more than one critic from New York is selected, then only one critic from Hollywood will be selected.
Frank and Katie cannot both sit on the panel.
Katie and Michelle cannot both sit on the panel.
If Michelle is selected, then both Pat and Roxie must join her on the panel.
If Michelle is selected to sit on the panel, then exactly how many selections are conclusively determined, including that of Michelle's?
Five
One
Three
Two
Four
Three
If Michelle is selected, then Pat and Roxie must join her. So immediately we know that at least three selections are conclusively determined.
The final two slots, however, could be filled in by either Frank, Grayson, or Helen (but only one, because we already have two Hollywood critics on the panel).
Another Hollywood critic (Quentin) could fill one of the two remaining slots, as could another Chicago critic (namely, Larry---Katie is out because Katie and Michelle cannot both be selected).
So, at most, only three slots are conclusively determined.
Example Question #62 : Grouping Games
A boy band (composed of Henry, Ralph, and Viktor) will play one song a day in a six-day music festival from Sunday to Friday. They have 10 total songs and will play a different song each day. Two songs will be chosen from among the three songs written by Henry – 1, 2, and 3: two from among the four songs written by Ralph – 4, 5, 6, and 7; and two from the songs written by Viktor – 8, 9, and 10. The following rules also apply:
- If song 5 is selected, then song 2 is also selected.
- If song 4 is selected, then neither songs 2 nor 6 can be selected.
- If song 8 is selected, then neither songs 10 nor 7 can be selected.
- If both songs 2 and 6 are selected, then song 2 is played at some time before song 6.
- Song 8 cannot be played on Thursday unless one of Ralph’s songs is played on Sunday.
Which song must be played at the music festival?
Song 6
Song 9
Song 2
Song 3
Song 10
Song 9
The rules state that songs 2 and 6 must be left out if song 8 is selected; and songs 10 and 7 must be left out if song 8 is selected. Therefore, the answer choices for songs 2, 6, and 10 can be eliminated. This leaves the answer choices for songs 3 and 9 respectively. According to Rule 3, if song 8 is selected then song 10 cannot be selected and therefore, song 9 must be played. If song 8 isn’t played, then the other two Viktor songs, 9 and 10, must be played. In either case, song 9 must be played.
Example Question #63 : Grouping Games
A boy band (composed of Henry, Ralph, and Viktor) will play one song a day in a six-day music festival from Sunday to Friday. They have 10 total songs and will play a different song each day. Two songs will be chosen from among the three songs written by Henry – 1, 2, and 3: two from among the four songs written by Ralph – 4, 5, 6, and 7; and two from the songs written by Viktor – 8, 9, and 10. The following rules also apply:
- If song 5 is selected, then song 2 is also selected.
- If song 4 is selected, then neither songs 2 nor 6 can be selected.
- If song 8 is selected, then neither songs 10 nor 7 can be selected.
- If both songs 2 and 6 are selected, then song 2 is played at some time before song 6.
- Song 8 cannot be played on Thursday unless one of Ralph’s songs is played on Sunday.
Which song CANNOT be selected with song 5 for the music festival?
Song 7
Song 6
Song 8
Song 10
Song 4
Song 4
This question can be answered using Rule 1 and 2. If song 5 is played, then song 2 must be played. Meanwhile, song 4 cannot be played when song 2 is played. Therefore, playing both songs 4 and 5 for the music festival is impossible. The other songs listed in the answer choices work fine when song 5 is played.
Example Question #64 : Grouping Games
A landscaper is deciding which flowers to plant in a client's yard. The flowers available are Hydrangeas, Irises, Jasmine, Kingcups, Lilacs, Marigolds and Oleander. His choice must conform to the following restrictions:
If he does not choose Jasmine, he must choose Hydrangea
If he chooses Marigold, he must also choose Oleander
If he chooses Iris, he cannot choose Hydrangea
He cannot choose Kingcup unless he chooses Iris
If he chooses Lilac, he must also choose Kingcup
Which of the following is a complete and accurate list of flowers he could choose to include?
Hydrangea, Marigold, Jasmine
Jasmine, Lilac, Iris
Hydrangea, Marigold, Oleander, Jasmine
Hydrangea, Marigold, Iris, Oleander
Lilac, Kingcup, Iris, Oleander
Hydrangea, Marigold, Oleander, Jasmine
This question can be answered simply through elimination by rule violation. Any answer that does not have one or the other of Hydrangea and Jasmine can be eliminated. Any answer that has Marigold but not Oleander can be eliminated. Any answer that has Hydrangea in the same group with Iris can be eliminated. Any answer that has Lilac without Kingcup can be eliminated, leaving us with only the correct answer.
Example Question #65 : Grouping Games
A landscaper is deciding which flowers to plant in a client's yard. The flowers available are Hydrangeas, Irises, Jasmine, Kingcups, Lilacs, Marigolds and Oleander. His choice must conform to the following restrictions:
If he does not choose Jasmine, he must choose Hydrangea
If he chooses Marigold, he must also choose Oleander
If he chooses Iris, he cannot choose Hydrangea
He cannot choose Kingcup unless he chooses Iris
If he chooses Lilac, he must also choose Kingcup
If he chooses Hydrangea, what is the maximum number of other flowers he can also choose?
One
Four
Three
Zero
Two
Three
If he chooses Hydrangea, we can eliminate Iris. Eliminating Iris eliminates Kingcup, which eliminates Lilac. All of the remaining flowers, namely Jasmine, Oleander and Marigold, can all be chosen with Hydrangea and with each other; therefore, three more flowers can be chosen when Hydrangea is chosen.
Example Question #66 : Grouping Games
There are two movie theaters in the city of Aires, the Cineplex and the Triplex. The owners of these two movie theaters have made an arrangement as to the showing of various movie genres. There are exactly four genres that these owners have been discussing: action, comedy, drama, and horror.
The showing of movies within these genres must be in accord with the following:
Each movie theater must always show exactly three films from three of the four genres.
At least one of the theaters must show both an action film and a drama film.
Whichever theater shows a comedy film must also show a horror film.
The Cineplex always shows an action film.
Which one of the following must be true?
The number of action films is greater than the number of drama films.
The Triplex shows an action film.
The number of action films is equal to the number of drama films.
The Triplex shows a horror film.
The Cineplex shows a drama film.
The Triplex shows a horror film.
There is no way to avoid having a horror film being played at the Triplex. We can see this to be so if we consider, first, that when a comedy is shown a horror film must also be shown. That means if an action, comedy, and horror film is shown at the Cineplex, then an action and drama film must be shown at the Triplex (since at least one theater must show both an action and drama film). But what third film can be shown at the Triplex? Only a horror film, because showing a comedy film would necessitate showing a horror film, but there aren't enough slots to permit that. The upshot is that no matter how the film genres are divided up, the Triplex ends up showing a horror film.
Example Question #67 : Grouping Games
There are two movie theaters in the city of Aires, the Cineplex and the Triplex. The owners of these two movie theaters have made an arrangement as to the showing of various movie genres. There are exactly four genres that these owners have been discussing: action, comedy, drama, and horror.
The showing of movies within these genres must be in accord with the following:
Each movie theater must always show exactly three films from three of the four genres.
At least one of the theaters must show both an action film and a drama film.
Whichever theater shows a comedy film must also show a horror film.
The Cineplex always shows an action film.
Which one of the following could be a complete and accurate list of the movie genres shown in each of the theaters?
Cineplex: comedy, drama, horror
Triplex: action, drama, horror
Cineplex: action, drama, horror
Triplex: action, comedy, drama
Cineplex: action, comedy, drama
Triplex: action, comedy, drama
Cineplex: Action, Drama, Horror
Triplex: Action, Comedy, Horror
Cineplex: action, comedy, horror
Triplex: action, comedy, horror
Cineplex: Action, Drama, Horror
Triplex: Action, Comedy, Horror
Because a comedy film must be accompanied by a horror film, the sequence of action, comedy, drama must be eliminated. Likewise, the sequence for the Triplex involving action, comedy, and drama must be eliminated.
Because at least one of the theaters must show an action and a drama film, the sequence of action, comedy, and horror must be eliminated.
Finally, Cineplex must show an action film, so the option specifying comedy, drama, and horror for the Cineplex must be eliminated.
Example Question #68 : Grouping Games
There are two movie theaters in the city of Aires, the Cineplex and the Triplex. The owners of these two movie theaters have made an arrangement as to the showing of various movie genres. There are exactly four genres that these owners have been discussing: action, comedy, drama, and horror.
The showing of movies within these genres must be in accord with the following:
Each movie theater must always show exactly three films from three of the four genres.
At least one of the theaters must show both an action film and a drama film.
Whichever theater shows a comedy film must also show a horror film.
The Cineplex always shows an action film.
Which one of the following must be false?
Both theaters show a comedy film.
Exactly one of the theaters shows an action film.
Both theaters show a horror film.
Both theaters show a drama film.
Exactly one of the theaters shows a drama film.
Both theaters show a comedy film.
Both theaters cannot show a comedy film. This conclusion follows from the rule that at least one of the theaters must show both an action film and a drama film. This rule precludes the showing of a comedy film in the theater showing those two genres, since the showing of a comedy film entails also showing a horror film.
Example Question #69 : Grouping Games
A social psychologist is conducting a study involving six individuals who are from three regions in the country. Fred, Greg, and Helen are from the northeast. Kate, Lyle, and Norm are from the west. And Ted, Vickie, and Zach are from the south.
Due to certain demographic and other requirements for the study, the selection of these individuals for the study must meet the following conditions:
Fred and Helen are not both selected.
Norm and Ted are not both selected.
If Helen is selected, Kate must also be selected.
If Kate is selected, Norm must also be selected.
Which one of the following is an acceptable selection of individuals for the study?
Fred, Greg, Kate, Norm, Ted, Vickie
Greg, Helen, Kate, Norm, Vickie, Zach
Greg, helen, Lyle, Norm, Vickie, Zach
Fred, Helen, kate, Norm, Vickie, Zach
Greg, Helen, Kate, Lyle, Vickie, Zach
Greg, Helen, Kate, Norm, Vickie, Zach
This is what one might call an "In-or-Out" game, since the task here is to determine who is selected and who is not (who is "in" and who is "out").
The rule that F and H cannot be together eliminates "F, H, K, N, V, Z."
The rule that N and T cannot be together eliminates "F, G, K, N, T, V"
The sequence "G, H, K, L, V, Z" violates the requirement that if H is selected, then so must be K and N (N is missing here). That same requirement also allows us to eliminate the sequence "G, H, L, N, V, Z."
So, we are left with "G, H, K, N, V, Z," which violates none of the conditions.
Example Question #70 : Grouping Games
A social psychologist is conducting a study involving six individuals who are from three regions in the country. Fred, Greg, and Helen are from the northeast. Kate, Lyle, and Norm are from the west. And Ted, Vickie, and Zach are from the south.
Due to certain demographic and other requirements for the study, the selection of these individuals for the study must meet the following conditions:
Fred and Helen are not both selected.
Norm and Ted are not both selected.
If Helen is selected, Kate must also be selected.
If Kate is selected, Norm must also be selected.
If Helen and Lyle are among the individuals selected for the study, which one of the following could be true?
Ted is selected.
Exactly one of the individuals from the west is selected.
Fred is selected.
Exactly two of the individuals from the west is selected.
Zach is selected.
Zach is selected.
Since H is selected, the "In" group must contain "H, L, K, N" and one other. The "out" group must contain "F and T." This simple application of the conditions allows us to eliminate the responses: "Fred is selected" and "Ted is selected."
Since we know that L, K, and N must be among those selected (the "in" group), and they are all from the west, we can eliminate the other two responses that specify that either only one or two individuals from the west are selected. That leaves us with the correct response, namely, that Zach is selected.
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