This is an explanation of the fourth logic game from Section III of LSAT Preptest 35, the October 2001 LSAT.
Seven professors were hired from 1989 to 1995. The professors are: Madison, Nilsson, Orozco, Paton, Robinson, Sarkis, and Togo (M, N, O, P, R, S, T). Each of them has at least one specialty but no two professors that were hired in the same or consecutive years share a common specialty.
This is a normal linear game in disguise. It has seven spaces, one after each other. Except this game calls them 1989-1995.
The only other thing that makes this game different is that more than one professor can be hired in each year.
We can draw the layout and the first rule like this:
The second rules tells us that M, O and T can’t be beside each other or hired in the same year. We could draw this a few different ways. I choose to put the variables underneath the spaces where they can’t go, and put lines through them.
We don’t know where O and T might go, so I drew the box with a suitcase handle to show that they can’t go beside each other, in either order.
(Note: a smarter method would have been to read through all the rules first, and notice you can put O directly in 1990)
The next rule tells you that N and R have a specialty in common. That means that N can’t go in 1990, 1991 or 1992.
The next rule lets you place N in 1989. The rule says that P and S come before M but after N.
The only place N could go is 1989.
Why? 1989, 90, 91 and 92 are the only spots before M, and you already know you can’t put N in 90, 91 and 92.
The next rule lets you solve almost everything. O was hired in 1990, and S can’t go beside O. So S can’t go in 89, 90 or 91. Since S has to go before M, S must therefore go in 1992.
And what about T? We know T can’t go in 92, 93 and 94. Now that O is in 1990, T can’t go in 89, 90 or 91, because O and T can’t go beside each other. So T has to go in 1995.
The only person left to place is P! P can go in 1990, 1991 or 1992, because P has to go between N and M.
As you can see, there’s no huge trick to getting this kind of diagram set up. All I’ve done is looked at each rule, and asked if I could make any deductions by combining the rule with the previous rules. Look for variables in common, and think about which variables are most restricted. The LSAT is expecting people to make these types of diagrams.
A big factor in the questions will be whether P ends up sharing a specialty with any professors.
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