Question
Two solid cubes each of volume 8,000 cm³ are joined end to end. Find the cost of painting the resulting cuboid all around at the rate of ₹25 per 100 cm².
The correct answer is
₹1,000
Each cube has a volume of 8,000 cm³, so the side length of each cube is ∛8000 = 20 cm. After joining the cubes, the cuboid has dimensions 20 × 20 × 40 cm. The surface area of the cuboid is:
Surface Area = 2 × (20 × 20 + 20 × 40 + 20 × 40) = 2 × (400 + 800 + 800) = 4000 cm²
The cost of painting = (4000/100) × 25 = ₹1,000.
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Important Questions from Mensuration
- The volume of a wall that is 5 times as high as it is broad and 8 times as long as it is high is 12.8 cubic meters. Find the breadth of the wall.
- If the radius of a sphere is increased by 2 cm, then its surface area increases by 704 cm\(^2\). Using \(\pi = \frac{22}{7}\), find the radius of the sphere after the increase.
- What is the perimeter of an equilateral triangle with side 13 cm?
- The perimeter of a square is 76 m. Its area (in $m^2$) is:
- A cylindrical rod has an outer curved surface area of 1800 cm$^2$. If the length of the rod is 52 cm, then the outer radius (in cm) of the rod, correct to two places of decimal, is:
Take $\pi = \frac{22}{7}$
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