Conservation of mass

$7\mathrm{.}25$ A venturi is a constriction formed in a pipe or tube for the purpose of mea. suring the pressure drop of a fluid. From the pressure drop measurement, the flow rate can be calculated. Hence, a venturi is sometimes referred to as a venturi meter or flow meter. For the venturi shown in Figure P$7\mathrm{.}25,$ the mass flow rate of water is $1\mathrm{.}75k\frac{g}{s}.$ Find the volume flow rate and average velocity at the entrance and the volume flow rate and average velocity at the constriction.