The figures show how a square sheet of paper is folded along the dotted lines (the arrows show the direction of folding) and then punched. Which option shows the sheet after it is completely unfolded?
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) →
When a folded sheet is opened, every hole is repeated as its mirror image across each fold line, the last fold being opened first. Here first the bottom half is folded up onto the top half and then the left half is folded over onto the right half. Opening the second fold copies the hole across the vertical fold line; opening the first fold then copies all of them across the horizontal fold line. So the opened sheet has 4 holes, placed symmetrically about the fold lines. A triangle’s copy across a fold line points the other way, as in a mirror.
Option (1) — Incorrect. It has an extra hole: the opened sheet has 4 holes, this option shows 5 holes.
Option (2) — Incorrect. The holes are in the right places, but the copies of the triangle are not turned over: across a fold line the copy must point the other way.
Option (3) — Incorrect. The copies across the vertical fold line (the second fold) are missing, so it shows only 2 holes.