A thermal chimney of circular cross section has outer and inner radii of 3m and 2m respectively. Find the cost of cement finishing for the inner and outer surface at Rs20 per sq.meter, if the height of the chimney is 56m.

• Ans 35200 Rs.
  Surface area of Cylinderical Section=2*pi*r*h
  Surface area of inner & outer surface=2*pi*h(r+R)=2*(22/7)*56(2+3)=1760 sq. m.
  Cost of finishing=20*1760=35200 Rs.
• 11 years agoHelpfull: Yes(65) No(7)
• In chimney the inner part is vacant.
  Therefore,
  Surface area of outer surface -surface area of inner surface=2*pi*h*R-2*pi*h*r =2*(22/7)*56(3-2)=352 sq. m.
  Cost of finishing=20*352=7040 Rs.
• 11 years agoHelpfull: Yes(7) No(23)
• surface area of outer and inner=2*(22/7)*3*56+2*(22/7)*2*56=175*20=3520
• 10 years agoHelpfull: Yes(2) No(6)