Correct Answer - Option 4 : 4.5 cm
Given:
⇒ Height of cylindrical pipe = 14cm
⇒ Volume of metal used = 99 cm
Formula:
Let r = radius of cylinder and h = height of cylinder
⇒ Volume of cylinder = πr2h
⇒ Curved surface area of cylinder = 2πrh
Calculation:
⇒ 2πRh - 2πrh = 44
⇒ R - r = 0.5cm
Then,
⇒ πR2h - πr2h = 99
⇒ (R2 - r2) = 2.25
⇒ (R + r)(R - r) = 2.25
∴ (R + r) = 4.5