Question

A golf ball strikes a hard, smooth floor at an angle 30.0° and,

Answer 1

I'm assuming that it's 30° from the horizontal

So the vertical velocity before the impact is v1 = 48.5 x sin(27) and after is v2 = - 48.5 x sin(27)

Then we use the equation I = m Δv so:
I = 0.0684 x (v2 - v1)
= -3.01 kg m/s ... (3 significant figures)
And since you only want the magnitude, just take the absolute value of that. Hope that helps