A cylindrical pillar is 50 cm in diameter and 3.5 m high.

Question

A cylindrical pillar is 50 cm in diameter and 3.5 m high. Find the cost of white washing its curved surface at the rate of Rs 1.25 per square metre.

Answer 1

Pillar is 50 cm in diameter and 3.5 m high(h)

Convert the diameter (d) to meters (m)

 

50 cm x    1 m      =  0.5 m is the diameter in meters

             100 cm

PI = π = 3.14

circumference (C) = πd = 3.14 x 0.5 m  =  1.57 m

 

The cylinder surface area is C x h  = 1.57 m x 3.5 m   = 5.5 m²

 

Cost of white washing =  5.5 m²  x Rs 1.25   = Rs 6.88

                                                       m²

 

 

 

Answer 2

Gf,

 

You have to first calculate the surface area of curved surface.

 

It is given by 2*pi*r*h

in this case it is 2*pi*.25*3.5 = 5.50 sq m

 

Cost id Rs 1.25 per sq m, so total cost is 5.50*1.25 = Rs 6.9

 

Answer 3

The circumference of the pillar is 50π cm., or 0.5 m. This would be one side of the surface. The other side is 3.5 m

The area to be painted is 0.5(3.5), or  17.5 m². 

 

The cost of white washing is 17.5 / 1.25, or 14.

 

The cost of white washing is $14.

Answer 4

The surface area of the curved surface of a cylinder is πdh, where d is the diameter and h is the height.

 

In order to figure out the area, though, you have to have all the numbers in the same units.  Since the rate for washing it is per square meter, let's get all the units in meters.

 

The height is already in meters, so let's convert the diameter to meters.  50 cm = 0.5 m, because there are 100 cm in a meter.

 

So the area is π * 0.5 * 3.5 which is approximately 5.5 m².  At 1.25 per square meter for washing, the cost for washing is RS 6.875.