Choose the correct option: 

A swimming pool is of dimensions 25 m × 12 m × 5.5 m. The cost of cementing its floor and wall at the rate of Rs 12.50 per square metre is _____.

Given,

length (l) of the swimming pool = 25 m

breadth (b) of the swimming pool = 12 m 

height (h) of the swimming pool = 5.5 m

The area of the four walls as well as the floor of the swimming pool is given by = 2h (l + b) + lb

$$\begin{gathered} =\left[2\times 5.5\left(25+12\right)+25\times 12\right] \\ =\left[11\right(37)+300] \\ =[407+300] \\ =707 m^2 \end{gathered}$$

Cost of cementing 1 m² of area = Rs 12.50

∴ Cost of cementing 707 m² of area = Rs (707 × 12.50) = Rs 8837.50

Thus, the cost of cementing the floor and the wall of the swimming pool is Rs 8837.50.