A cylindrical rod with a volume of 75π cubic centimeters is melted down and cast into a hollow cylindrical pipe with an inner radius of 1 centimeter and an outer radius of 2 centimeters. What will be the length of the new pipe?
Show answer & explanation
Correct answer: D
Explanation
Volume = 75π cm³, Inner radius = 1 cm, Outer radius = 2 cm
According to the formula:
Volume of hollow cylinder = πh(R² − r²)
75π = πh(2² − 1²)
= πh(4 − 1)
= 3πh
75π = 3πh
h = 75/3
= 25 cm