Question

a tank is 20 metre in length 15 metre in bread and 4 metre in depth find the cost of cementing it and a four walls @ rupees 50 per square metre

Answer 1

The area that needs to be cemented is the floor and the 4 walls

So total area = (l * w) + 2(l * h) + 2(w * h)
                     = (20*15) + 2(20*4) + 2(15*4)
                     = 300 + 160 + 120
                     = 120 m²

Cost of cementing = 50 per m²
Total cost of cementing = 120 * 50 = Rs 6000