A solution of sodium hydroxide of density 1650 kg/m3 and viscosity 50 mN s/m2 is agitated by a propeller mixer of 0.5 m diameter in a tank of 2.28 m diameter, and the liquid depth is 2.28 m. The propeller is situated 0.5 m above the bottom of the tank. What is the power which the propeller must impart to the liquid for a rotational speed of 2 Hz?