A $4-$bladed vane turbine mixer $($Np $=5\mathrm{.}31)$ with an impeller diameter of $2$ feet rotates at a rate of $100$ rpm$.$ What is the power imparted by the mixer? $($The density of water is $1\mathrm{.}94$ slugs$/$ft$3$ or $1,000$ kg$/$m$3)$ a$)1\mathrm{.}0$ hp b$)2\mathrm{.}8$ hp c$)60$ hp d$)89$ hp