Q.

A right circular hollow cylinder has an outer radius of R and inner radius of r. Which of the following statements hold true if h is the height of the cylinder

(i) Curved surface area of the cylinder =2π(R+r)h

(ii) Total surface area of the cylinder =2π(R+r)(R+h-r)

(iii) Total volume of the cylinder =π(R2-r2)h

(iv) Total volume of the cylinder =π(R2+r2)h

Choose the correct option from the following:

1 Only (iv)  
2 (i) and (iii)  
3 (i), (ii) and (iii)  
4 (i), (ii) and (iv)  

Ans.

(3)

Curved surface area = External curved surface area + Internal curved surface area

=2πRh+2πrh=2π(R+r)h

(ii) Total surface area =2πRh+2πrh+2(πR2-πr2)

=2π(R+r)h+2π(R+r)(R-r)

=2π(R+r)(R+h-r)

(iii) Total volume=πR2h-πr2h=πh(R2-r2)

 Option (c) is correct.