Answer
5.85 x $10^{7}$ N
Work Step by Step
Starting with Impulse-Momentum
F$\Delta$t = $\Delta$(mv)
We can divide both sides by the change in time
F = $\Delta$(mv)/$\Delta$t
In this problem, the velocity (v) is a constant 4.5 x $10^{4}$ m/s and the mass rate ($\Delta$m/$\Delta$t) is 1300 kg/s. From this, we can say that:
F = v*$\Delta$m/$\Delta$t
F = (4.5 x $10^{4}$ m/s)*(1300 kg/s)
F = 5.85 x $10^{7}$ N