Question

4. A metal sheet, 27 cm long, 8 cm. broad and 1
cm thick, is melted into a cube. The difference
between the surface areas of two solids is
A. 284 cm2 B. 286 cm2
C. 296 cm D. 300 cm
​

Answer 1

Volume of sheet = volume of cube

First we will calculate volume of metal sheet =l X b x h

= 27 x8 x1=216cm^3

So volume of the cube is also 216 cm^3

216=a^3

3√216

= 6

So surface area of sheet = 2(lb+bh+hl)

=2(27x8+8x1+1x27)

=502cm^2

And surface area of cube

=6a^2

=6 x6^2=216cm^2

Difference between surface area = 502-216=286cm^2

Answer 2

here is your answer mate....

surface area of cuboid will be.. 2(lb+bh+hl) = 2(27×8+8×1+1×27)

2(216+8+27)=2(251)=502 cm^2

although the cube is made from same cuboid volume of both will be same... hence,...

let side of cube be a

l×b×h = a^3

27×8×1=a^3

a= 3√216= 2×3=6

therefore.... surface area of cube= 6a^2 6×6^2=36×6=216cm^2

therefore difference between them will be 502-216=286cm^2 ans....

hope this helps you.....