Multiple choice

A company makes a metallic block having square bases with volume $640$ $cm^3$, and height $10$ cm. If Robin wants to paint the block with the paints at the rate of Rs $15$ per $cm^2$, then find the cost of painting Robin has to pay.

  1. Rs $5680$
  2. Rs $6595$
  3. Rs $6720$
  4. Rs $6690$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Volume = base_area * height = 640. base_area = 640 / 10 = 64. Since base is square, side = 8. Surface area to paint = 2 * base_area + perimeter * height = 2 * 64 + (4 * 8) * 10 = 128 + 320 = 448. Cost = 448 * 15 = 6720.

AI explanation

The square base area is the volume divided by the height, so 640 cm^3 divided by 10 cm equals a base area of 64 cm^2, meaning each side of the square base is 8 cm. The total surface area of the block is found by adding the lateral surface area (4 multiplied by base side multiplied by height, which is 320 cm^2) and the areas of the two square bases (2 multiplied by 64 cm^2), resulting in a total surface area of 448 cm^2. Multiplying this surface area by the painting rate of 15 rupees per cm^2 gives a total cost of 6720 rupees.

Keep practicing — related questions