Can someone explain this TFE question?

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jhanago

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What about this? This says that the answer is B. Wouldnt there have to be some holes along the top as well?

1628jyd.jpg
 
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Because B shows the cut out going all the way through the cube. You can see clearly in the front view that the the cut out does not go all the way through. Just halfway. Need the line at the top for the end view. If B and C both had the line across there would be no way to tell. Took me a while to see it! Quite tricky....
 
i remember this question, when I first saw it I was absolutely baffled but looking at it now I can see why its not B.

Im kinda bad at explaining these so bear with me, but choice B would mean that the "notch" goes all the way thru the cube, not just halfway. If it had gone all the way thru, you wouldnt see the middle solid and dashed lines in the top and front views. Only choice C satisfies this (as well as the other stuff, like depth etc.)

edit: damn im too late, no virgins for me ;(
 
There wouldn't be any holes along the top because as you can see, the second fold results in such a way that there isn't another "layer" of paper underneath--this happens because of the first fold. Finally, when you mentally unfold, you realize that there will be two holes in the first column in (#2, and #3), and when you unfold the first fold, hole punch #2 will be "copied over" to hole punch #1 because of symmetry.

Hope it wasn't too confusing!
 
Can someone help me figure out how these particular folds work? Because the first fold makes it from a 4 hole tall figure to a 3 hole tall figure. How does the second fold contain 4 holes tall again? Does that make sense?
 
Can someone help me figure out how these particular folds work? Because the first fold makes it from a 4 hole tall figure to a 3 hole tall figure. How does the second fold contain 4 holes tall again? Does that make sense?

jhanago,

The best thing you can do is to find a napkin, tissue or a paper. Fold it and punch 2 holes like the one in the problem and see it for yourself. It doesnt take that much time but this is the best way to learn. 🙂
 
Can someone help me figure out how these particular folds work? Because the first fold makes it from a 4 hole tall figure to a 3 hole tall figure. How does the second fold contain 4 holes tall again? Does that make sense?

Second fold is still 3 holes tall they just flipped it over to hide the fold. so they fold it once from 4 tall to 3 tall. then fold the left corner down to cover 3 rows of holes and flip it over so its three holes at its highest point then a fold going from 2 holes to one hole. so that fold does not cover the hole punched area. best thing is keep track how they have changed the position from its original and go from there. good luck hope this helps.
 
I agree with Wizi, I do the same thing when I get confused. Take a Square piece of paper, fold it and punch it. sometimes demo helps the best to figure it out and also helps in developing your imaginary skills for other probs. 😉
 
Thats a keyhole problem! Try using post-it notes and a hole punch, it works like a charm =)

Good Luck!
 
I know this is a butthole move of me to ask.. but can someone quickly make a video, webcam or anything, of them folding the paper and punching then unfolding? I tried it and it isn't working for me stilll... I think im folding wrong or something?
 
Yeah, I am also not getting how it goes from 4 holes tall to 3 holes tall.. I am trying to fold it with a piece of paper and just can't figure it out..

I make my first fold with the paper "portrait" style. I then turn the paper 90 degrees to the right and fold the bottom left. I punch the two holes and then unfold and rotate back to my starting point. I get all the holes on B except for the top left.. What am I doing wrong?
 
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I could be wrong, but I think the confusion is as to why the left side shifts in one hole. The reason for this is because you're pulling the bottom left corner up one row further BEYOND the top of the first fold, which causes the left side to be pulled in by one hole width. If you folded the bottom left corner upward just flush to the top of the first fold, then you'd have a 1x3 region on the right side that is not affected. You can see this when you're folding your paper, you just have to pay attention when you're bringing the bottom corner up past the top of the first fold edge and watch the left edge pull in. Hope this helps.
 
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