b$.$ Two reservoirs $($having water$)$ are connected by three pipes in series of diameter $\backslash (10\mathrm{.}0\backslash$mathrm$\{$~cm$\},15\mathrm{.}0\backslash$mathrm$\{$~cm$\}\backslash ),$ and $20\mathrm{.}0$ cm respectively. Each pipe has a length of $100\mathrm{.}0$ m $.$ If the difference in the water levels of the two tanks is $50\mathrm{.}0$ m $,$ compute the discharge through them. Calculate the $\backslash \%$ error in flow rate if minor losses are ignored. Take the friction factor, f as $0\mathrm{.}03.$

$(8$ marks$)$