This is an explanation of the second logic game from Section I of LSAT Preptest 30, the December 1999 LSAT.
Six messages were left on an answering machine by Fleure, Greta, Hildy, Liam, Pasquale, or Theodore (F, G, H, L, P, T). You must determine the possible sequence and who exactly left the messages based on the rules.
Game Setup
This is a complex game. It has elements of in-out grouping, sequencing, linear, and numerical distribution.
Despite that, this game doesn’t have to be hard. You just need a good diagram.
The first two rules are critical. Don’t just write them down. Think about what they mean.
The numerical distribution of messages Is important
There are six people, and six messages. Only one person can leave more than one message, and they can only leave three, at most.
For example, let’s say one person left three messages. We’d still need three other people to leave messages, for a total of four people. There are always at least four people in the game.
We could also have one person leave two messages, or six people could all leave one message.
So we have these scenarios for the number of messages left by different people. The numbers refer to the number of messages left by each person, not who left the messages:
- 3-1-1-1. (four people)
- 2-1-1-1-1 (five people)
- 1-1-1-1-1-1 (six people)
Make sure you understand the numerical distribution, and keep it in mind. It’s crucial for solving the game. I’ll discuss it more it more later, once we look at the rules about who can leave messages.
The third rule is important to remember, because it doesn’t connect with any other rules.
When I find a rule that can’t be connected, I will take a few seconds to consciously repeat it. I will also look at all of the rules again before starting the game. I want to burn them into my brain for eight minutes and forty-five seconds. If I forget that H being in first forces P into sixth, this game will be hard.
Now, for the in-out rules. If G is in, F and P are in.
The fifth rule makes the fourth rule partly redundant. If F is in, P and T are in.
So we don’t need to say that G causes P to be in. G forces F in, and F forces P in. We get a simpler diagram this way; there’s no need to say the same thing twice.
I’ve drawn a unique diagram for this game. F causes P and T to be in, but P is in front of T (If F is in).
So I’ve added a sequencing rule to the diagram. The line between P and T shows that P is before T when F is in.
Next, if P is in, then H and L are in, and H is before L.
I’ve added the same sequencing rule as a reminder that H is before L when P is in.
There are other ways you could draw these rules, but this is the simplest way I’ve seen. Simple diagrams allow you to view all of the rules at once. And while you could draw the sequencing rules separately, why would you? This way, you can’t forget them.
Who can leave messages if there are multiple messages by one person?
Now, lets think about the numerical distribution. We need at least four people to leave messages. Let’s think about who doesn’t have to be in. We can have as low as four people leaving messages. If G is in, everyone is in. So if we have only four people, then G would have to be out.
If F is in, P, T, H and L are also in. That’s five people.
So if only four people leave messages, G and F are out. P, T, H and L are in. H is before L, but P and T can be in any order. The rule about their order only applies when F is in. Also, note that one person leaves three messages when four people are in.
If five people leave messages, then F is in, and one person leaves two messages. P does come before T in this scenario. If all six people are in, then everyone leaves one message, and all of the rules apply.
For clarity, the three scenarios are:
- Six people in, all the rules apply.
- Five people in: G is out, F is in and all the rules apply. One person leaves two messages.
- Four people in: G and F are out, one person leaves three messages. H is before L, but P doesn’t have to be before T.
If you understand the diagram and these three scenarios, the game is easy.
Go over the setup and try to draw things yourself if you’re still uncertain about any of this.
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