Question

the inner radius of a cylindrical tunnel is 9 m and 21 m long find the cost of painting the inner surface of the tunnel at the rate of rupes 8 per meter square

Answer 1

The cost of painting the inner surface of the tunnel is Rs.9504.

Step-by-step explanation:

Given : The inner radius of a cylindrical tunnel is 9 m and 21 m long.

To find : The cost of painting the inner surface of the tunnel at the rate of rupees 8 per meter square ?

Solution :

The painting will be done only on the curve surface portion of the tunnel.

So, The area of the painting is

$A=2\pi rh$

r= 9 m is the radius

h= 21 m i the height

$A=2\times \frac{22}{7}\times 9\times 21$

$A=1188\ m^2$

The rate of rupees 8 per meter square,

Cost of the painting is

$\text{Cost}=\text{Rate}\times \text{Area}$

$\text{Cost}=8\times 1188$

$\text{Cost}=Rs.9504$

Therefore, the cost of painting the inner surface of the tunnel is Rs.9504.

#Learn more

The outer surface of cube of side 5m is painted. If the cost of painting is 1per 100cm find the total cost of painting the cube

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