$131$

$4\mathrm{.}1\mathrm{.}4.$ At a water$-$treatment plant, water $(68F)$ flows from tank A to tank B at a rate of $0\mathrm{.}50$ cfs through a $3-$in$.-$di ameter, cast$-$iron pipe that is $200$ feet long. Determine the difference in water surface elevation between tanks $($open to the atmosphere$)$ if there are two bends