The ratio of diameter to height of a Borosil cylindrical glass is 3 : 5. If the actual diameter of the glass is 6 cm, then the curved surface area of the glass is :

1. 120π

2. 60π

3. 30π

4. 18π

Given,

Ratio of diameter to height of a Borosil cylindrical glass is 3 : 5.

$\Rightarrow \dfrac{d}{h} = \dfrac{3}{5} \\[1em] \Rightarrow \dfrac{6}{h} = \dfrac{3}{5} \\[1em] \Rightarrow h = \dfrac{6 \times 5}{3} \\[1em] \Rightarrow h = 10 \text{ cm}.$

Radius = $\dfrac{\text{Diameter}}{2} = \dfrac{6}{2}$ = 3 cm.

By formula,

Curved surface area of glass = 2πrh

= 2π × 3 × 10

= 60π cm².

Hence, Option 2 is the correct option.