Three solid cubes of edges 3cm, 4cm, 7cm are melted together to make a new cube. 218 cm³ of this melted material is lost in the process. The surface area of the newly formed cube is -
Answer & explanation
Correct answer: option 3
Total volume of melted material = (3)3 + (4)3 + (7)3
= 27 + 64 + 343 = 434cm3
Since 218cm3 is lost, therefore, remaining material = 434 - 218 = 216 cm3
Side of new cube = \(\sqrt[3]{216 }\) = 6 cm
Surface area = 6 × (side)2
= 6 × 36
= 216 cm2