The diameter of plain cement concrete pipes used for sewerage system is __________
(a) 20mm
(b) 30mm
(c) 90mm
(d) 63mm
The question was asked by my college professor while I was bunking the class.
This intriguing question originated from Material for Sewers in portion Construction of Sewers, Sewer Appurtenances and Sewage Pumping of Environmental Engineering