Problem understanding cube problem on Crack

[riggs]

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I am confused about this cube counting problem. I accidentally closed the window before getting a picture of the back row by itself so hopefully I can explain this. I did some copying and pasting on the second picture to explain what it looked like since I didn't get a picture copied. Where I had a problem is when counting cubes with two and four sides. I counted 5 two-sided cubes. (Looking at the second picture, I marked the blue cube on the left as two sided because I didn't envision the block behind it). I missed the four sided cubes too because of the cube in the back. The computer said that there was on cube on the back row (3rd row) on the left side (where I put the red arrow). Since you can't see anything there on the first picture, and it's not at least three high (where I can see it), why would there be a cube there?


Picture 1:

Picture 2:

 

[riggs]

^

 

[riggs]

Anyone have any tips for this one?

 

[Andre3k]

umm... just look at it. there are five cubes with four painted sides. 😎

 

[Andre3k]

my bad your right i dont see it either.

 

[Kkae]

K, for cube counting i just use a grid numbered 1-5 which represents the sides each cube would have then start at the base of the diagram and count up.

So how i looked at it: if u look to the left of the diagram u'll c three columns, that means there's also three columns on the right of the diagram contrary to the 2 which are immediately visible. Considering a third column to the right u'll c that behind that purple cube (with the arrow) there's another right behind it...but of course u can't c it because it's 1. all the way to the back and 2. on the same level as the one in front of it.

 

[riggs]

umm... just look at it. there are five cubes with four painted sides. 😎

That makes sense, but I don't understand why that back left cube would be there.

It would be easier to see if I had the original picture with just all blue cubes. Just imagine the first picture with all blue cubes. My point is that the cube pointed to in the back left of the second picture shouldn't be there. Why would there be a cube back there? (Just ignore the second picture and look at the first one. Would you place one cube in the back left corner, third row, without seeing the second picture?

 

[riggs]

K, for cube counting i just use a grid numbered 1-5 which represents the sides each cube would have then start at the base of the diagram and count up.

Fair enough, but that still doesn't explain why there is a cube in the back left corner.

 

[riggs]

I'll try to explain my problem better.

 

[Kkae]

Some of these things are just always tricky like that. Ex: going thru CDP i c some things that would just be impossible to know, but i guess if u had an eye for it u'd actually c it. at first look i kinda saw that there wud b a cube there plus the arrow helps.

 

[riggs]

Some of these things are just always tricky like that. Ex: going thru CDP i c some things that would just be impossible to know, but i guess if u had an eye for it u'd actually c it. at first look i kinda saw that there wud b a cube there plus the arrow helps.

I put the arrow there. The orginal figure did not have an arrow. I think the cube should not be there (error on CDP's part).

 

[Kkae]

assuming symmetry there would also b three colums on the left. Plus, i think the arrow helps to recon that

 

[Kkae]

(whoa! u respond fast!)
It is possibly an error.
I somehow "assumed" a third column on the left also. Which isn't safe, hmm...

 

[riggs]

(whoa! u respond fast!)
It is possibly an error.
I somehow "assumed" a third column on the left also. Which isn't safe, hmm...

Yeah, I'm on the computer doing other stuff, that's why I replied quick. Here's another way to word it. I know it's sometimes hard to understand what people are saying on PAT problems. And you might be right about assuming a third row on the left, I just don't see it.

 

[Kkae]

hmm...c wat ur saying.
mistake or trick question then, ur right.
As for me: lucky assumption.

 

[Andre3k]

.

 

[klpennin]

Yah, there is no way to know that there is a block there unless in the original picture you can see it. On the DAT, they say only to assume that supporting blocks are there, no extras. So this must be a mistake unless if you could see it in the original view.

 

[riggs]

Yah, there is no way to know that there is a block there unless in the original picture you can see it. On the DAT, they say only to assume that supporting blocks are there, no extras. So this must be a mistake unless if you could see it in the original view.

That's what I thought. Just must be a mistake because you can't see it in the original picture and it's not a supporting cube.