$2.$ How many rapid sand filter boxes are needed to handle the flow rate of $1($m $^3)/$ s if the desired dimension of a filter box is $10$m $*10$m and the design loading rate is $100$m $^3*$ d $^-1*$ m $^-2$ If the single media filters are replaced with dual media filters that operate with a loading rate of $300$ m$^3*$ d$^-1.$m$^-2$ how will that affect the number of filter boxes required in this plant?