A cylindrical rod has an outer curved surface area of 9900 cm$$^2$$​. If the length of the rod is 82 cm, then the outer radius (in cm) of the rod, correct to two places of decimal, is:
Take $$\pi = \frac{22}{7}$$​​

Correct option is B

Given:

Outer curved surface area of the cylindrical rod = 9900 cm²

Length of the rod (height of the cylinder) = 82 cm

Formula Used:

The curved surface area (CSA) of a cylinder is given by:

CSA = 2πrh

Where:

r is the outer radius of the rod

h is the height (length) of the cylinder

Solution:

$$9900 = 2 \times \frac{22}{7} \times r \times 82 \\ \ \\9900 = \frac{44}{7} \times r \times 82 \\ \ \\9900 = \frac{3608}{7} \times r \\ \ \\9900 \times 7 = 3608 \times r \\ \ \\r = \frac{69300}{3608} \approx 19.21 \, \text{cm}$$​