Question

a plot of land in the form of rectangle has a dimension 240m x 180m . a draiinlet 10m wide is dug all around it (on the outside) and the earth dug out is evenly spread over the plot, increasing its surface level by 25cm . find the depth of the drainlet.

Answer 1

Since the rectangular surface level is increased, we can calculated the volume of earth dug and added on the rectangular plot.Volume of earth dug = 240m x 180m x 0.25m = 10800 m3 This volume is also the volume of the drainlet.= 2(240m x 10m x d m) + 2(180m x 10m x d m) = 10800 m3.d = depth = 1.29 m