Q.29. A container opens at the top and made up of metal sheet is in the form of a frustum of a cone of height 16 cm with diameters of its lower and upper ends are 16 cm and 40 cm respectively. Find the cost of metal sheet sued to make the container, if it costs Rs. 10 per 100$c{m}^2. \left(Use \mathrm{\pi }=3.14\right)$

Dear Student,

Radius (r₁) of upper end of container = 20 cm

Radius (r₂) of lower end of container = 8 cm

Height (h) of container = 16 cm

Slant height (l) of frustum =

Area of metal sheet used to make the container

= π (20 + 8) 20 + π (8)²

= 560 π + 64 π = 624 π cm²

Cost of 100 cm² metal sheet = Rs 10

Now the cost of 624pi cm^2 sheet = 624*3.14*10/100 =Rs. 195.936 =Rs.196 (Approx)

Regards.