Question

a cylindrical vessel open at the top has a diameter of 20 cm and height of 14 cm find the cost of tin plating in on it on the side inside at rate 1 per 100 cm square

Answer 1

For Finding The Cost Of Tin Plating We Should Find The TSA.

But It Is Open At The Top 

So Remaining TSA 

Hence Area Of Top Must Be Excluded

So Remaining TSA  = 2*pie*r*h + pie*r*r

Substituting Values

TSA = 2*22/7*10*14 + 22/7*10*10  

TSA = 880+2200/7  = 8360/7 m2

Cost = 50 Paise = Re 1/2

Cost = 8360/7*1/2 = 597.14

So Approximate Cost = Rs 597