The length and breadth of n rectangular field of a village are 20 m and 15 m respectively. For construction of pillars in the 4 corners of that field 4 cubic holes huving length of 4 m are dug out and the soils removed arc dispersed on the remaining land. Calculate the height of the surfaces of the field that is increased by it.

Explanation

The volume of soil of one hole `=4^3` cu-m = 64 cm
`therefore` the volume of soil of 4 holes `=64 xx 4` cu - m = 256 cu -m
Let the height of the surface of the field be increased by h metres. `therefore` the volume of the soil thus increased `= 20 xx 15 xx h ` cu- metres
As per condition `20 xx 15 xx h =256 ` or ,`h= (256)/(20xx 15)=0.85 ` metre ( approx)