# Mensuration-17

### From Homeworkwiki

**A solid is composed of a cylinder with hemispherical ends. If the whole length of the solid is 108 cm and the diameter of the**

**hemispherical ends is 36 cm,**

find the cost of polishing the surface at the rate of 7 cents per sq. cm. (Take π = 3.1416)

find the cost of polishing the surface at the rate of 7 cents per sq. cm. (Take π = 3.1416)

**Solution:** Radius of the cylinder = Radius of the hemisphere

= 36/2 = 18 cm

Length of the cylinder = 108 - (18 + 18) = 72 cm

Surface area of the cylinder = 2 π r h

= 2 x 3.1416 x 18 x 72 sq. cm

Surface area of two equal hemisphere = 2 x 2 π r^{2}

= 4 π r^{2}

= 4 x 3.1416 x 18 x 18 sq. cm.

Total surface area = (2 x 3.1416 x 18 x 72) + (4 x 3.1416 x 18 x 18) sq. cm

= 12214.5 sq. cm (approximately)

Cost of polishing 1 sq. cm = 7 cents

Total cost = $ 7/100 x 12214.5

= $ 855.02