RRB NTPC Mains or Stage 2 Model Paper 6 with solutions

Question : 24 of 119

Marks: +1, -0

A solid metallic cube of edge 4 cm is melted and recast into solid cubes of edge 1 cm. If x is the surface area of the melted cube and y is the total surface area of all the cubes recast, then what is x : y?

2 : 1
1 : 2
1 : 4
4 : 1

Validate

Solution:

= (4)^3 = 64 cm 3

Volume of recast cube

= (1)^3 = 1 cm3

∴Total surface area of cube : Total surface area of recast cube = x : y

⇒ x : y = 6(4)^2 : 6(1)^2 × 64 = 1 : 4

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