Discussion

The curved surface area of a right circular cylinder of base radius 3 cm is 94.2 cm². The volume (in cm³) of the cylinder is (Take π = 3.14)

Answer: B

The volume is 141.3 cm³.

First find the height from the curved surface area, \(2\pi rh\):

\[ \begin{aligned} 2 \times 3.14 \times 3 \times h &= 94.2 \\ 18.84h &= 94.2, \quad h = 5\ \text{cm} \end{aligned} \]

Then the volume:

\[ \begin{aligned} V &= \pi r^{2} h = 3.14 \times 9 \times 5 \\ &= 141.3\ \text{cm}^{3} \end{aligned} \]

113.04 is \(\pi r^{2} h\) with h = 4, and 125.6 and 138.6 do not follow from r = 3 and h = 5. With the given \(\pi = 3.14\) the answer is 141.3.

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