UPSC Prelims 2000·GS1·science-and-technology·materials and robotics

A rectangular piece of iron sheet measuring 50 cm by 100 cm is rolled into a cylinder of height 50 cm. If the cost of painting the cylinder is Rs. 50 per square metre, then what will be the cost of painting the outer surface of the cylinder?

Dalvoy logo
Reviewed by Dalvoy
UPSC Civil Services preparation
Last updated 23 May 2026, 3:31 pm IST
  1. ARs. 25.00Correct
  2. BRs. 37.50
  3. CRs. 75.00
  4. DRs. 87.50

Explanation

To find the cost of painting, we first need to determine the area of the outer surface of the cylinder. 1. Area Calculation: The rectangular sheet itself forms the curved surface of the cylinder. The area of the sheet is length multiplied by breadth. Area = 100 cm multiplied by 50 cm = 5000 square cm. 2. Unit Conversion: Since the cost is given per square metre, we convert the area from square cm to square m. 1 square metre = 10,000 square cm. So, 5000 square cm = 5000 divided by 10,000 = 0.5 square m. 3. Cost Calculation: The cost of painting is Rs. 50 per square metre. Total Cost = Area multiplied by Rate = 0.5 square m multiplied by Rs. 50 = Rs. 25.00. Therefore, option A is the correct answer.
science-and-technology: A rectangular piece of iron sheet measuring 50 cm by 100 cm is rolled into a cylinder of height 50 cm. If the cost of pa

Related questions

More UPSC Prelims practice from the same subject and topic.