A square piece of paper is folded as shown by the dotted lines and the arrows, and the folded paper is punched as shown in the last figure. Choose the figure that shows the paper when it is unfolded.
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) →
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 upper-left part is folded onto the lower-right part and then the upper-right part is folded onto the lower-left part. Opening the second fold copies the hole across the diagonal fold line (top-left to bottom-right); opening the first fold then copies all of them across the diagonal fold line (top-right to bottom-left). 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. 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 (2) — Incorrect. It has an extra hole: the opened sheet has 4 holes, this option shows 5 holes.
Option (4) — Incorrect. Only the second fold has been opened: the copies across the diagonal fold line (top-right to bottom-left) are missing, so it shows only 2 holes.