Question

A closed metallic cylinder has its base diameter 56 cm and it is 2.25 M high and find the cost of metal used to make it if it costs rs 80 per square metre

Answer 1

Diameter of base of closed metallic cylinder = 56 cm

So, its radius; r = 56/2 = 28 cm = 0.28 m

Height; h = 2.25 m

Total surface area of metallic cylinder = 2πr(r+h) = 2×22/7×0.28(0.28+2.25) = 2×22/7×0.28×2.53 =4.4528 m2 

Cost of making per square meter of metal = Rs.80

So, total cost of making the whole metal = 4.4528×80 = Rs.356.224

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