A $800$ mm$$ main carrying $2\mathrm{.}4\frac{m^3}{s}$ branches into two pipelines between points A and $B,$ one $1200$ m $.$ long with a diameter of $450$ mm and one $1350$ m $.$ long with a diameter of $600$ mm $.$ Both pipes come together at point $B$ and continues as a single $800$ mm pipe. Assuming values of $f$ equal to $0\mathrm{.}022,0\mathrm{.}033$ and $0\mathrm{.}024$ respectively for the $900mm,600mm$ and $450$ mm diameter pipes.

$16.$ Determine the rate of flow of the $450$ mm pipe.

A$.0\mathrm{.}88\frac{m^3}{s}$

C$.0\mathrm{.}91$

B$.0\mathrm{.}76$

D$.0\mathrm{.}83$

$17.$ Determine the rate of flow of the $600$ mm pipe.

A$.1\mathrm{.}75$

C$.1\mathrm{.}49$

B$.1\mathrm{.}18$

D$.1\mathrm{.}05$

$18.$ Determine the pressure head at $B$ if the pressure head at $A$ is $200$ m $.$

A$.94\mathrm{.}94$ m

C$.97\mathrm{.}23$ m

B$.90\mathrm{.}65$ m

D$.99\mathrm{.}46m$