Question

The base radius of an iron cylinder is 15 centimetres and its height is 32 centimetres. It is melted and recast into a cylinder of base radius 20 cm. What is the height of thid cylinder?

Answer 1

Given ,

radius of first cylinder = 15cm

height of first cylinder = 32 cm

Volume = πr^2h

= 22/7×15×15×32

= 22/7×225×32

= 22/7×800

=3.14×800

=2512cm^3

radius of second cylinder=20cm

height=?

Volume of first cylinder will be equal to volume of second cylinder

so,

22/7×20×20×h = 2512

22/7×400×h = 2512

h=(2512×7)/(22×400)

h=17584/8800

h= 1.8cm(approx.2cm)

Answer 2

Volume of Cylinder

pi×r²h

22/7 × 15² × 32

22/7 × 225 × 32

158400/7 = 22628.5

ATQ

pi × r² × h

22/7 × 20² × h = 22628.5

22/7 × 400 × h = 22628.5

22 × 400h = 158400

400h = 7200

h = 18 cm

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