$3\mathrm{.}44$ A fire hose nozzle has a diameter of $1\frac{1}{8}$ in$.$ According to some fire codes, the nozzle must be capable of delivering at least $250ga\frac{l}{m}in.$ If the nozzle is attached to a $3-$in$.-$diameter hose, what pressure must be maintained just upstream of the nozzle to deliver this flowrate?