Question

A joker’s cap is in the form of a right- circular cone whose base radius is 7 cm and height is 24 cm. The area of the sheet required to make 10 such caps is

A) 550 cm²

B) 5500 cm²

C) 55000 cm²

D) None

Answer 1

Correct option is: B) 5500 cm²

We have r = 7 cm and h = 24 cm.

Area of sheet required to make 1 joker's cap

= \(\pi rl = \pi r\sqrt {r^2+h^2}\) (\(\because\) l = \(\sqrt {r^2+h^2}\)))

= \(\frac {22}7 \times 7\sqrt {7^2+24^2}\)

= \(22\sqrt{49+576} = 22\sqrt{625} = 22 \times 25 = 550 cm^2\)

\(\therefore\) Area of sheet required to make 10 such caps = 550 \(\times\) 10 \(cm^2\)= 5500 \(cm^2\).

Answer 2

Correct option is: B) 5500 cm²