In/Out Games (LSAT)

When posting about LSAT logic games on this blog, I'd like to focus on certain aspects of different types of games that I often see students overlook. There's a type of game on the LSAT often referred to as an in/out game. It's a grouping game, but unlike other grouping games, there are only 2 groups, an in group and an out group.

Let's assume that 8 friends (A, B, C, D, E, F, G, H) are trying out for the school basketball team but only 5 of those 8 friends will be chosen for the team. In addition, they'll be chosen in a specific order based on how they perform at the tryouts. 

These rules indicate an in/out game since the in group will be the friends chosen for the team and the out group will be the friends who are not chosen.  There's also a sequencing element to this game because the friends in the in group are going to be ordered. There is no sequencing element to the out group, however. There will be 5 friends in the in group, and 3 in the out group. A good board for this game could be the following: 

_ _ _ _ _ | _ _ _ 

You really don't need to order the out group in a line the way I've done here, but it's essential (for the reasons that follow) that you note somehow that there are 3 elements in the out group. 

Now let's come up with a few rules:

~If A makes the team then B doesn't make the team

~If E makes the team, then E is chosen 3rd.

~ C only makes the team if D makes the team and if D makes the team then D is chosen first. 

~ G and H can't both make the team.

On an in/out game, it's important to note carefully how many elements comprise the out group. Because once that out group fills up, lots of rules trigger and the questions can become quite easy to solve. 

Let's look at the rules.

We know that both A and B can't make the team. It's possible that they both don't make the team but it's not possible that they both make the team. Therefore, at least one of the slots in the out group is always filled with A or B or both.

The same can be said for G and H. Maybe they both are out but they can't both be in. Either G or H is out or both G and H are out. So at least 2 of the 3 out slots are already filled just from these rules. 

You might notice that if D doesn't make the team, then C doesn't make the team. That's the contrapositive of rule #3. But that would be impossible here. We know that at least 2 of the 3 out slots are already filled and if both D and C don't make the team that would be at least 4 players not making the team which is impossible. So a subtle inference to make in this game would be that D has to make the team and that D will be placed in slot 1.

Let's assume that all three slots in the out group fill up. Something like this:

_ _ _ _ _ | B H F

This would be a very favorable thing in terms of ordering. Now, rules that were previously conditional no longer are. 

We know the following:

D _ E _ _ | B H F

As for A, C, and G, they'd get to flip around among those 3 open slots. 

Keep these points in mind for any in/out group you might encounter on the test!