Answer
Please see the attached picture for the answer.
Work Step by Step
Pie charts are prepared by finding the relative frequencies of all classes.
X's shaded portion = 0.4 $\times$ 360 = 144 Degrees.
Y's shaded portion = 0.45 $\times$ 360 = 162 Degrees
Z's shaded portion = 0.15 $\times$ 360 = 54 Degrees.