Question

the radius of a right circular cylindrical pole isn28cm and height is 5.8m find the cost of polishing it's .C.S.A at the rate of 2₹ sq.m​

Answer 1

Given :

• The radius of a right circular cylindrical pole is 28 cm.

• The height of a right circular cylindrical pole is 5.8 m.

To find :

• The cost of polishing it's .C.S.A at the rate of 2₹ m² =?

Step-by-step explanation :

It is Given that,

The radius of a right circular cylindrical pole is 28 cm.

The height of a right circular cylindrical pole is 5.8 m Or 580 cm.

Now,

As We know that,

Curved Surface Area of Cylinder = 2πrh

Substituting the values in the above formula, we get,

= 2 × 22/7 × 28 × 580

= 2 × 22 × 4 × 580

= 176 × 580

= 102,080.

Now, As question is saying we have to find it area in metre so 102,080 cm² in metre = 10.208.

Therefore, Curved Surface Area of Cylinder = 10.208 m².

Now,

The cost of polishing it's .C.S.A at the rate of 2₹ sq.m [Given]

So,

Curved Surface Area of Cylinder × ₹ 2

Substituting the values, we get,

= 10.208 × 2

= 20.416.

Therefore, the cost of polishing it's .C.S.A at the rate of ₹ 2 per m² = ₹ 20.416

Answer 2

Given :-

• Radius of the right cylindrical pole = 28 cm

• Height of the cylinder = 5.8 meters

Required to find :-

• Cost of polishing it's CSA ?

Formula used :-

$\Large{\dagger{\boxed{\rm{ CSA \ of \ a \ cone = 2\pi rh }}}}$

Units Conversion :-

Before solving this question we need to convert some units from one unit to another unit .

Here, we need to convert the height from metres to centi-meters .

So,

As we know that ,

1 meter = 100 centi-meters

So,

5.8 m = ? centi-meters

=> 5.8 x 100

=> 580 centi-meters

Hence,

• Height of the cylinder = 580 cm

Solution :-

Given information :-

• Radius of the cylinder = 28 centi-meters

• Height of the cylinder = 580 centi-meters

We need to find the cost of. polishing it's CSA at the rate ₹2 per m²

In order to find the cost of polishing it's CSA , first we need to find it's CSA .

So,

Using the formula ;

$\Large{\dagger{\boxed{\rm{ CSA \ of \ a \ cone = 2\pi rh }}}}$

Let, take π = 22/7

Substituting the values ,

$\rightarrow{\sf{ {CSA}_{cylinder} = 2 \times \dfrac{22}{7} \times 28 \ cm \times 580 \ cm }}$

$\rightarrow{\sf{ {CSA}_{cylinder } = 2 \times \dfrac{22}{ \cancel{7} } \times { \cancel{28 } }^{ \large{4 }} \ cm \times 580 \ cm }}$

$\rightarrow{\sf{ {CSA}_{cylinder} = 2 \times 22 \times 4 \ cm \times 580 \ m }}$

$\rightarrow{\sf{ {CSA }_{cylinder} = 102,080 cm^2 }}$

Here ,

We need to convert this CSA from cm² into m²

So,

As we know that ;

1 meter = 100 centimetres

squaring on both sides

( 1 meter )² = ( 100 centimetres )²

1 m² = 10,000 cm²

Hence,

1 cm² = 1/10,000 m²

So,

1,02,080 cm² = ? m²

This implies,

=> 102080/10000

=> 10.208 m²

Hence,

• CSA of the cylindrical = 10.208 m²

However,

It is also mentioned that ,

Cost of polishing the CSA oat the rate per m² = ₹ 2

So,

Cost of polishing 10.208 m² = ?

=> 10.208 x 2

=> ₹ 20.416

=> ₹ 20 ( approximately )

Therefore,

Cost of polishing it's CSA = ₹20 ( approximately )