which valves need to be turned on to make pipe connect in parallel and in series $(5).$

$\backslash$table$[[$Pipes connect in parallel,Pipes connect in series$],[,]]$

Why some of the pressure measurements are negative $(5).$

Pick one trial data to determine the head loss through each pipe when the pipe connected in series $(1$ GPM$=0\mathrm{.}002676$ cfs$)(20).$

Pick one trial data to determine the flow rate through each pipe when the pipe connect in parallel $(20).$