A cube has a volume of 343 cm3. If its edges are increased by 20%, the new volume will be:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → 592.704 cm3
The volume of a cube is the cube of its edge, so the edge is found first from the volume, then increased by 20%.
Edge \(=\sqrt[3]{343}=7\) cm
New edge \(=7\times1.2=8.4\) cm
New volume \(=8.4^{3}=\) 592.704 cm3
Shortcut:
Every edge is multiplied by 1.2, so the volume is multiplied by \(1.2^{3}=1.728\)
New volume \(=343\times1.728=592.704\) cm3, without finding the edge