pressure problem?

Pressure difference between points at dia = 300mm and dia = 150mm
= 1 x (1.25 x 1000)g N/m^2
= 12,263 N/m^2

Using Bernoulli Equation:
12263 = (1/2).(1.25 x 1000).[(V2)^2 - (V1)^2]
i.e. (V2)^2 - (V1)^2 = 19.62 (m/s)^2 ------------ (1)
where V1 and V2 are the water flow speed respectively at the two specified points.

Cross-sectional area at diameter 300mm
= (pi).(0.15)^2 m^2 = 0.07069 m^2
Cross-sectional area at diameter 150 mm
= (pi).(0.075)^2 m^2 = 0.01767 m^2

Using Continuity Equation at the same two points:
q = (V1).(0.07069) = (V2).(0.01767) where q is the theoretical water flow rate
i.e. V2 = 4(V1)
Hence, equation (1) becomes,
16(V1)^2 - (V1)^2 = 19.62
V1 = 1.144 m/s
Thus q = 1.144 x 0.07069 m^3/s = 0.08087 m^3/s

Given the actual water flow rate = 0.0037 m^3/s
hence the coefficient of discharge = 0.0037/0.08087 = 0.0458