How much area of a metal sheet is required to make an open cylindrical container of radius 2.5 m and height 14m?
Answers
Answer:
. A plastic box 1.5 m long, 1.25 m wide and 65 cm deep is to be made. It the top. Ignoring the thickness of the plastic sheet, determine:
(i) The area of the sheet required .for snaking the box.
(ii) The cost of sheet for it, if a sheet measuring 1 m2 costs Rs. 20.
Sol: (i) Here, l = 1.5 m, b = 1.25 m


∵ It is open from the top.
∵ Its surface area = [Lateral surface area] + [Base area]
= [2(l + b)h] + [l × b]
= [2(1.50 + 1.25)0.65 m2] + [1.50 × 1.25 m2]
= [2 × 2.75 × 0.65 m2] + [1.875 m2]
= 3.575 m2 + 1.875 m2 = 5.45 m2
∵ The total surface area of the box = 5.45 m2
∴ Area of the sheet required for making the box = 5.45 m2
(ii) Rate of sheet = Rs. 20 per m2
Cost of 5.45 m2 = Rs. 20 × 5.45

⇒ Cost of the required sheet = Rs.109
Answer:
surface area of cylinder = 2πrh
= 2×22/7×2.5×14 = 220 m^2
answer 220m^2 sheet required