Question

solve this question A hollow cylindrical tube open at both ends is made of iron 3 cm thick. if the external diameter be 56 cm and the length of the tube be 182 cm,find the number of cubic cmin it?

Answer 1

external diameter = 56 cm
external Radius = R = 28 cm
Inner Radius = r = 28-3 = 25 cm
h = 182 cm
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The number of cubic cm if iron
= Volume of hollow cylinder
= πR^2h - πr^2h
= πh(R^2-r^2)
= (22/7)×(182)× [(28×28)-(25×25)
= 22×26×(784-625)
= 572 × 159
= 90948 cubic cm
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Answer 2

volume of hollow cylinder =pi. {R^2-r^2}.h
where R is the external radius
r is the internal radius
and h is the length of cylinder.
so,
R=28 cm
r=28cm-3cm=25cm
h=182 cm
now,
volume of cylinder =22/7 x {28^2-25^2} x 182 =22/7 x 3 x 53 x 182 cm^3
=90948 cm^3