Question

In the figure, you see the frame of a lampshade. It is to be covered with a decorative cloth. The frame has a base diameter of 20 cm and height of 30 cm. A margin of 2.5 cm is to be given for folding it over the top and bottom of the frame. How much cloth is required for making lampshade?

• A. 2002 $c{m}^2$
• B. 2020 $c{m}^2$
• C. 2000 $c{m}^2$
• D. 2200 $c{m}^2$

Answer 1

Answer: (D)

2200 $c{m}^2$

Diameter of the base of lampshade, d = 20 cm
radius r = $\frac{d}{2}$ = $\frac{20}{2}$ cm ;
height = 30 cm
Margin over the top and bottom = 2.5 cm + 2.5 cm = 5 cm
Hence total length of the cloth used
h = 30 cm + 5 cm
h = 35 cm
The cloth required for covering the lampshade = 2$\pi$$rh$ = 2 X $\frac{22}{7}$ X 10 X 35 = 2200 cm${}^2$