A rapid$-$mixing basin is to be designed for a water coagulation plant $,$and the design flow for the basin is $4\mathrm{.}0$ MGD$.$ The basin is to be square with a depht egual to $1\mathrm{.}25$ times the widht. The velocity gradient is to be $900$ seconde negative at $50$ degree fahrenheit, and the detention time is $30$ seconde$.$ Determine: a$)$ The basin dimensions if increments of $1$ in$.$ are used. b$)$ The input horsepower required. c$)$ The impeller speed if a vane$-$disc impeller with six flat blades is employed and the tank is baffled. The impeller diameter is to be $50\%$ of the basin width.