The side of a square is 10 cm. How many times will the new perimeter become if the side of the square is doubled?
2 times
4 times
6 times
8 times
Step 1: Formula for the perimeter of a square is
\( P = 4 \times s \)
Step 2: With side \( s = 10\,\text{cm} \), the original perimeter is
\( P_{\text{old}} = 4 \times 10 = 40\,\text{cm} \)
Step 3: If the side is doubled, the new side becomes
\( s_{\text{new}} = 2 \times 10 = 20\,\text{cm} \)
Step 4: New perimeter is
\( P_{\text{new}} = 4 \times 20 = 80\,\text{cm} \)
Step 5: Compare new and old perimeters:
\( \dfrac{P_{\text{new}}}{P_{\text{old}}} = \dfrac{80}{40} = 2 \)
Conclusion: The perimeter becomes 2 times when the side is doubled. (Option A)
Quick tip: Perimeter changes in the same ratio as the side. Doubling side \(\Rightarrow\) perimeter doubles. (Area would become 4 times, not perimeter.)