B$.$ Two open tanks, $(2)$ and $(3)$ in the figure, are to be supplied with water from a reservoir $(1)$ through a pipe branching at $(0),15m$ below the surface level in the reservoir, the surface levels in the tanks $2$ and $3$ being $3m$ above and $3m$ below the junction point, respectively. The single pipe $($supplying pipe from tank $1)$ will be $60m$ long and $7\mathrm{.}5cm$ in diameter, while the branched pipes will have lengths of $30m$ and $45m$ for the higher and lower tanks, respectively. What should be the diameters of these branched pipes in order that each has the same capacity of $0\mathrm{.}26\frac{m^3}{m}in?$ The Darcy friction factor is $f=0\mathrm{.}032.$