Q7

[hilarykustoff]

Can someone please explain #7? Thanks!

[timmydoeslsat]

This is a global question that can be answered quickly with an effective diagram.

To shed some light on the diagram, we know that we have 7 trucks. We know that this will be a multi-row ordering game, where we would want to have 2 rows, one row for the truck names and another row for its color, either G or else R.

G/R : _ _ _ _ _ _ _
Truck:_ _ _ _ _ _ _
-------1 2 3 4 5 6 7

We know that only S is 6th.

G/R : _ _ _ _ _ _ _
Truck:_ _ _ _ _ S _
-------1 2 3 4 5 6 7

We know that Y comes before T and W.

We also know that exactly 2 of the trucks that arrive before Y are red.

We know that the reds cannot be consecutive.

We need to think about the places Y can go. I initially had this in mind to potentially frame this game in all of the places Y can go. As you quickly see, there is only one place Y can go. To be able to accommodate T and W after Y, Y could not go 7 or 5. But it could go fourth. And when we think about Y going fourth with exactly 2 reds coming before it, we see that Y could not go earlier than 4th either, as it would force the reds to be consecutive.

So we now have this:

G/R : R G R G _ _ _
Truck:_ _ _ Y T S W
-------1 2 3 4 5 6 7

*T/W are interchangeable.

We also have an ordering of Z-U with X being a random variable. These three variables will make up some order in the first three slots.

When I first saw this question, my first mode of attack was to see if the test writers threw a Y in one of the answer choices, which would have been a freebie, but hey it happens at times. Not this time though.

Next plan of attack was to note the last three slots of the diagram. No way could S be a red along with one of T/W. And that is what answer choice B does for us. It is the right answer.

[ManhattanPrepLSAT1]

Great explanation Timmy!