Imagine a game in which we need to group elements. There are six elements to group (A, B, C, D, E, F) but only 5 spaces in which to group them. In addition, the five elements must be sequenced, 1-5 from left to right.
So, the board would look something like the following:
_ _ _ _ _ | _
The in group requires we sequence the five elements, and the out group requires we place the one element.
Further assume a couple rules:
--If C is in then C is 3rd
--If B is in then D is immediately before B.
--If A is in then A is either 4th or 5th.
At the outset, there isn't so much for us to do here. These rules are all conditional and because we don't know which element is out, none of these conditional rules tell us very much. But look out for situations when there are only a few (and in this case only one) element in the out group, along with the conditional rules. Because the moment the out group fills up, the conditional rules trigger.
An example:
"Which of the following must be true if E is out."
So, we now have this:
_ _ _ _ _ | E
But because E is out, we also know quite a few things. We know that if C is in it has to be third and now we do know that C is in. So, it has to be third.
_ _ C _ _ | E
But that's not all. We also know that B is in and if B is in then D is immediately before B. That gives us two possibilities here:
(1) D B C _ _ | E
or
(2) _ _ C D B | E
But we also know that A is in and if A is in, A has to be 4th or 5th, so possibility (2) doesn't work here.
We're left with:
(3) D B C A _ | E
or
(4) D B C _ A | E
That's about as far as we can take it. We know nothing about F so A and F are interchangeable in (3) and (4). F is sometimes called a "floater," since it's not limited by any rules.
The Takeaway:
When you have a grouping game with conditional rules and you've filled up the out group, begin to apply all of those conditional rules that are now no longer conditional. Lots of information will then come about to allow you to answer the questions.
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