A tank is 25 m long, 12 m wide and 6 m deep. The cost of plastering its walls and bottom at 75 paise per sq. m, is:

Solution (By Examveda Team)

$$\eqalign{ & {\text{Area}}\,{\text{to}}\,{\text{be}}\,{\text{plastered}} \cr & = \left[ {2\left( {l + b} \right) \times h} \right] + \left( {l \times b} \right) \cr & = \left\{ {\left[ {2\left( {25 + 12} \right) \times 6} \right] + \left( {25 \times 12} \right)} \right\}{m^2} \cr & = \left( {444 + 300} \right){m^2} \cr & = 744{m^2} \cr & \therefore {\text{Cost}}\,{\text{of}}\,{\text{Plastering}} \cr & = Rs.\,\left( {744 \times \frac{{75}}{{100}}} \right) \cr & = Rs.\,558 \cr} $$