Question

In a temple 20 cylindrical pillars. The radius of each pillar is 14cm and height is 5m. find the total cost of painting the curved surface area of pillars at the rate of Rs.10 per mtr.

Answer 1

Hint:
To find the total cost of painting on 20 pillars of radius 14cm and height 5m we will multiply the total curved surface area of 20 pillars with per ${m^2}$ cost.

Complete step-by-step answer:
Given: we have given the number of pillars which are 20 and the radius of pillar is 14cm and height of pillar is 5m and the rate of cost of painting is Rs. 10 per ${m^2}$ .
First we will convert the unit of radius from cm to m,
Which is $
  14cm = \dfrac{{14}}{{100}}m \\
  14cm = 0.14m \\
$
So, now the radius is $0.14m$ and height is 5$m$ .
Now, we will calculate the curved surface of one pillar which is $2\pi rh$ .
Where, $r$ represents the radius of pillar and $h$ represents the height of pillar.
Now, substitute the value of radius and height of the pillar in the formula of curved surface area.
$
   = 2 \times \pi \times \left( {0.14} \right) \times \left( 5 \right) \\
   = 4.4{m^2} \\
$
So, we found out the curved surface area of one pillar which is $4.4{m^2}$ .
Now, we will calculate the total curved surface area of 20 pillars of the same dimension.
To find the curved surface area of 20 pillars we will multiply the curved surface area of one pillar with the 20 pillars.
Mathematically, $
   = 4.4 \times 20 \\
   = 88{m^2} \\
$
So, the total curved surface area of 20 pillars is $88{m^2}$ on which painting is to be done.
So, to find the cost of painting we will multiply the total curved surface area with the rate of per ${m^2}$.
Mathematically, $88 \times 10 = Rs.880$
So, the total cost for painting the 20 pillars of radius $0.14m$ and height $5m$ with the rate of Rs.$10$ per ${m^2}$ is Rs. 880

Note:
In this type of problems first convert the units into a single and same unit of all the dimensions as we convert the radius because it is given in th $cm$ and we want the answer according to $m$.
For these types of conversion you should know the all conversions of units.