A square sheet of paper is folded along the dotted line in the direction of the arrow, and holes are then punched through all the layers, as shown in the figures. How will the sheet look when it is opened out?
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 the top half is folded down onto the bottom half, so opening it copies each of the 2 holes across the horizontal fold line. So the opened sheet has 4 holes, placed symmetrically about the fold line. 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 (4) — Incorrect. One of the copies is missing: the opened sheet has 4 holes, this option shows only 3 holes.