Volume and Surface Area of Solid Figures
- Three metal cubes of sides 5 cm, 4 cm and 3 cm are melted and recast into a new cube. The length of the edge of this cube, is ?
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Volume of new cube = (5)3 + (4)3 + (3)3 cm3
Correct Option: A
Volume of new cube = (5)3 + (4)3 + (3)3 cm3
= 126 cm3
Edge of this cube = (6 x 6 x 6)1/3 = 6 cm
- If each side of a cube is doubled, then its volume? .
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Let the edge of original cube = x cm
Edge of new cube = (2x) cm
Ratio of their volumes = x3 : (2x)3Correct Option: D
Let the edge of original cube = x cm
Edge of new cube = (2x) cm
Ratio of their volumes = x3 : (2x)3
= x3 : 8x3
= 1 :8
Thus the volumes be comes 8 times.
- The surface area of a cube is 726 m2. Its volume is ?
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Surface area = 6a2 = 726
Correct Option: B
Surface area = 6a2 = 726
⇒ a2 = 121
⇒ a = 11 cm
∴ Volume of the cube = (11 x 11 x 11) cm3
= 1331 cm3
