Question

Three cubes of silver with edges 3 cm, 4 cm and 5 cm are melted and recast into a
single cube. Find the cost of coating the surface of the new cube with gold at the rate
of 3.50 per square centimetre.
[Hint. If a cm is the edge of a new cube, then a3 = 33 + 43 + 50
93 = 216 = (6)3 => a = 6.]​

Answer 1

Explanation:

Volume of first cube= 3×3×3

=27

Volume of 2nd cube=4×4×4

=64

Volume of 3rd cube=5×5×5

=125

Sum= 27+64+125

=216

cube root of 216 = 6

Total cost = 6×3.50

=21.

Therefore, 21Rs.