Design rapid sand filter bed$($s$)$ for treating max $8\mathrm{.}5$ x $106$

litres per day with rate of filtration as $5500$ l$/$h$/$m$2.$ Assume

L$/$B $=2\mathrm{.}5.$

Compare it with Slow sand filter beds with rate of filtration

as $120$ l$/$h$/$m$2.$