A rectangular paper of 20 cm × 8 cm is folded 3 times. Each fold is made along the line of symmetry, which is perpendicular to its long edge. The perimeter of the final folded sheet (in cm) is
Answer
(A)
Explanation
Each fold halves the sheet’s current long side, because the fold line is perpendicular to the long edge of the sheet as it is at that moment:
- Fold 1: 20 × 8 becomes 10 × 8.
- Fold 2: the long edge is now 10 cm, so 10 × 8 becomes 5 × 8.
- Fold 3: the long edge is now 8 cm, so 5 × 8 becomes 5 × 4.
The final 5 cm × 4 cm sheet has perimeter \(2(5 + 4) = 18\) cm. Halving the 20 cm side all three times would give 2.5 × 8 and a perimeter of 21 cm (option D), but by the third fold that side is no longer the long edge.
Answer: A