High School

An iron pipe has an outer radius of 4 cm and is 5 cm long. Its curved surface area needs to be painted. Find the cost of painting at the rate of Rs. 14 per square meter.

a) Rs. 176
b) Rs. 308
c) Rs. 1232
d) Rs. 2156

Answer :

Final answer:

To determine the painting cost, the curved surface area of the pipe is calculated using the formula CSA = 2πrH, with the given dimensions, and multiplied by the painting rate per square meter to find the total cost, which is approximately Rs. 176. Therefore, the correct answer is option a) Rs. 176.

Explanation:

The question involves finding the cost of painting the curved surface area of a cylindrical pipe. To calculate the curved surface area of a cylinder, we use the formula Curved Surface Area (CSA) = 2πrH, where r is the radius and H is the height of the cylinder. For a pipe with an outer radius of 4 cm and height of 5 cm, the CSA will be 2π(4 cm)(5 cm) = 40π cm2. Converting this area into square meters by dividing by 10,000 (since 1 m2 = 10,000 cm2), we get 40π / 10,000 m2. Multiplying the area by the cost per square meter gives the total cost of painting. Therefore, the cost to paint the curved surface of the pipe is 40π/10,000 m2 × Rs. 14/m2. Simplifying this, we find the cost is approximately Rs. 176, which is option (a).