# Maths

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A hollow spherical metal ball has internal radius 1cm. If the metal is 1/2 cm thick, find the volume of metal ( Take pi equals 22/7)

• Maths -

volume (if solid metal) = (4/3)π r^3
= (4/3) π (1.5)^3
= 4.5π

Hollow part = (4/3)π(1^3 = 4π/3

so volume of metal = (9/2)π - (4/3)π
= (19/6)π
or appr. 9.95 , (nobody uses 22/7 for π, we all have calculators)

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