Answers

2015-10-14T17:18:34+05:30
Volume of old cube =a³
⇒(12)³=1728 cm³
No.of cubes =8
Volume of old cube = 8* volume of 1 new cube
1728=8*a³
1728/8=a³
12/2=a
6 cm=a
Surface area of old cube/ surface area of new cube=6*(12)²/6*(6)²
=144/36=4/1=4:1
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surface area of a cube = 6a square, then the surface area of older cube = 6 * 12square =>864 sq.cm and the surface area of new cube = 6* 6 square =>216
arre you have cancelled the 6 on both numerator and denominator . I am REALLY SORRY. Nice job
2015-10-14T18:02:10+05:30
Side of a large cube(a) = 12cm
volume of the cube = (12³)cm³
 => 1728 cm³
eight small cubes of equal volumes are cut from the larger one 
∴volume of larger cube = 8* volume of one small cube.
=>1728 = 8 * volume of small cube
=>1728/8 = volume of small cube
∴volume of one small cube = 216.
then side of the smaller cube = ∛216 = 6cm
 The ratio of surface area of larger cube  and small cube = 864:216 = 4:1
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