Solution:
Given diameter, d = 3.5 m
So radius, r = 3.5/2 = 1.75
Depth, h = 12 m
Volume of the cone = (1/3)r2h
=(1/3)×(22/7)×1.752×12
= (22/7)× 1.752×4
= 38.5 m3
= 38.5 kilolitres [1 kilolitre = 1m3]
Hence the volume of the conical pit is 38.5 kilolitres.