Water flows between two adjacent parts of a vertically sided service reservoir through a submerged 0.3m diameter orifice (CD = 0.60) in a common dividing wall. The first reservoir measures 45m by 30m in plan and initially contains water to a height of 5.0m above the centre of the orifice. The second tank is 20m by 30m in plan and the initial water level can be assumed to be at the same height as the centre of the orifice. Assuming that there is no other flow into or out of the reservoirs: (a) how long will it take for the two water levels in the tanks to become equal? (b) what is the final depth of water in the tanks, measured above the centre of the orifice?