Given:
Radius of first cylinder, r1 = 4 cm
Diameter of recast cylinder, D2 = 12cm
Height of recast cylinder, h2 = 9 cm
Formula used:
Volume of a cylinder = π r2 h
Calculations:
Volume remains the same, V1 = V2
⇒ π × (r1)2 × h1 = π × (r2)2 × h2
Radius of recast cylinder = r2 = D2/2 = 6 cm
⇒ 42 × h1 = 62 × 9
⇒ 16 h1 = 36 × 9
⇒ h1 = 20.25 cm
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