Q18

[Virg.elizabeth.gordon]

I am confused as to why green couldn't be in box one? I understand the WG block, but I am confused as to why the answer is (B) box 3.

[ohthatpatrick]

Since we have two white balls, we'll have three red balls according to rule 1. (We can't have four red balls because there has to be at least one green)

So we have WW, RRR, and G.

If we put G in 1, then where would we get our WG chunk from?

We're all out of G's.

G _ _ _ _ _ (and all that's left is 2 W's and 3 R's)

Make sense why G can't be in 1?

Could it be in 3? Sure.
W W G R R R is fine.

Could it be in 4?
_ _ _ G _ _

Well, we have 3 R's we have to use, and they all have to be higher (to the right) of G. So we don't have enough spaces left to get it done.

That's the same problem with putting G in box 5 or 6.

Hope this helps.

[CharlesS800]

I began this problem by considering the set up if there are two white balls. With two white balls, you must have three red and one green. Because there is only one green ball, it must form a W/G chunk with one of the white balls, a chunk that must end up beneath all of the red balls. Knowing that it must be beneath the three red balls, I could eliminate answer choices C, D, and E, which would all create scenarios so that there would be a red ball beneath a green ball, which is a no no. Knowing that W must come below G, I could also then eliminate answer choice A, which would then not be possible, as G could only be in slots 2/3 in this scenario. This left me with answer choice B, which I then selected.