Question
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 $\pi = \frac{22}{7}$
The correct answer is
5.51
Given:
Curved surface area (CSA) = 1800 cm²
Height (h) = 52 cm
We Know:
CSA of cylinder = 2 × π × r × h
r = CSA ÷ (2 × π × h)
Now,
⇒ r = 1800 ÷ (2 × 3.1416 × 52)
⇒ r = 1800 ÷ (326.725)
⇒ r = 5.51 cm
So, Outer radius = 5.51 cm
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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 spherical tank has a diameter of 10 metres. What is the volume of the spherical tank? (Use $\pi = 3.141$)
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