To develop this problem it is necessary to apply the equations concerning Bernoulli's law of conservation of flow.
From Bernoulli it is possible to express the change in pressure as
Where,
Velocity
Density
g = Gravitational acceleration
h = Height
From the given values the change of flow is given as
Therefore between the two states we have to
The flow rate will have changed to 54.77 % of its original value.