Question:
A field is in the form of a rectangular length 18m and width 15m. A pit 7.5m long, 6m broad and 0.8m deep, is dug in a corner of the field and the earth taken out is spread over the remaining area of the field. Find out the extent to which the level of the field has been raised.
Solution:
Let 'h' metres be the rise in the level of field
Volume of earth taken out from the pit $=7.5^{*} 6^{*} 0.8=36 \mathrm{~m}^{3}$
Area of the field on which the earth taken out is to be spread $=18$ * $15-7.5$ * $6=225 \mathrm{~m}^{2}$
Now, Area of the field * h = Volume of the earth taken out from the pit
⇒ 225 ∗ h = 7.5 ∗ 6 ∗ 0.8
⇒ h = 36/225 = 0.16 m = 16 cm