Question : The volume of a right circular cone is 308 cm³ and the radius of its base is 7 cm. What is the curved surface area (in cm²) of the cone? (Take $\pi=\frac{22}{7}$)

Option 1: $22 \sqrt{21}$

Option 2: $44 \sqrt{21}$

Option 3: $22 \sqrt{85}$

Option 4: $11 \sqrt{85}$

Question : A right circular cone is 3.6 cm high, and the radius of its base is 1.6 cm. It is melted and recast into a right circular cone with a radius of 1.2 cm at its base. Then the height of the cone (in cm) is:

Option 1: 3.6

Option 2: 4.8

Option 3: 6.4

Option 4: 7.2

Question : The circumference of the base of a right circular cone is 44 cm and its height is 24 cm. The curved surface area (in cm²) of the cone is: (Take $\pi=\frac{22}{7}$)

Option 1: 528

Option 2: 572

Option 3: 550

Option 4: 440

Question : The lateral surface area of a frustum of a right circular cone, if the area of its base is 16$\pi$ cm², the diameter of the circular upper surface is 4 cm and the slant height is 6 cm, will be:

Option 1: $30\pi$ cm²

Option 2: $48\pi$ cm²

Option 3: $36\pi$ cm²

Option 4: $60\pi$ cm²

Question : A hemisphere of lead of radius 4 cm is cast into a right circular cone of height 72 cm. What is the radius of the base of the cone?

Option 1: 1.63 cm

Option 2: 1.35 cm

Option 3: 1.33 cm

Option 4: 1.45 cm