A hemisphere of radius 30 cm is moulded to form a cylinder of height 180 cm. The diameter of the cylinder is:

20 cm

We know that,

Volume of hemisphere = \(\frac{2}{3}\) πr³

Volume of cylinder = πR²h

We have,

Radius = r = 30 cm

Height = h = 180 cm

According to the question,

πR²h = \(\frac{2}{3}\) πr³

= R² × 180 = \(\frac{2}{3}\) × 30 × 30 × 30

= R² = \(\frac{54000}{540}\) 

= R² = 100

= R = 10 cm

Then, Diameter of the cylinder = 2 × 10 = 20 cm