Question

A metal cuboid of dimension 22 cm. x 15 cm. x 7.5 cm. was melted and cast into a cylinder of height 14 cm. What is its radius?

Answer 1

Vol.cuboid-22×15×7.5
=2475 cm^3
Height of cylinder=14
Vol.cylinder =Vol. cuboid =2475
Vol. cylinder =pie×r×r×h
2475=22/7×r×r×14

Hence,r^2 = 56.25
So,r=7.5

Answer 2

vol. of cuboid = 22 x 15 x 7.5

height (h) of cylinder = 14

when melted and recasted only the vol. changes

thus,

vol. of cuboid = vol. of cylinder

22 x 15 x 7.5 =3.14 x rxr x 14

r square = (22 x 15 x 7.5) / (3.14 x 14)

              = sqrt(56.30)

               =7.5

therefore radius = 7.5 cm