A hollow sphere of internal and external diameters 4 cm and 8 cm respectively is melted to form a solid cylinder of base diameter 8 cm. What is the height of the cylinder?

4.67 cm

Volume of hollow sphere = \(\frac{4 }{3 }\)π(R³ -r³)

Volume of solid cylinder = πR²h

According to the question,

\(\frac{4 }{3 }\)π(R³ -r³) = πR²h

\(\frac{4 }{3 }\) x (4³ - 2³) = 4²h ( π gets cancelled)

\(\frac{4 }{3 }\) x 64 - 8 = 16h

\(\frac{4 }{3 }\) x 56 = 16h

h = \(\frac{224 }{48 }\) 

h = 4.67 cm