A milk container is made of metal sheet in the shape of frustum of a cone whose volume is . The radii of its lower and upper circular ends are 8 cm and 20 cm respectively. Find the cost of metal sheet used in making the container at the rate of Rs. 1.40 per .

Question

Philoid · Accepted Answer

Given: volume of the frustum = 10459 cm³

Radii of lower and upper ends resp.: r’ = 8cm and r’’ = 20cm

Volume =

⇒ h = 16cm

Let slant height be l

Slant height, l =

⇒ l = 20cm

Total surface area of the frustum = π(r’ + r’’)l + π r’² + π r’’²

= π(20 + 8)20 + π (20)² + π (8)²

= 3218.29 cm²

cost of metal sheet used in making the container at the rate of Rs. 1.40 per = 3218.28 × 1.40

= Rs4506