Three solid cubes of edges 3 cm, 5 cm, 9 cm are melted together to make a new cube. 557 cm³ of this melted material is lost in the process. The surface area of the newly formed cube is -
Answer & explanation
Correct answer: option 4
Total volume of melted cubes = (3)3 + (5)3 + (9)3
= 27 + 125 + 729 = 881 cm3
Since (557 cm3) is lost, remaining material weighs = 881 - 557 = 324 cm
Volume of the cube = (side)3
⇒ 324 = (side)3
⇒ side = \(\sqrt[3]{324 }\) = 8 cm
Surface area = 6 × ⇒ (side)2 = 6 × 64 = 384 cm2