Alfredo, Barbara, and Cathy throw darts at a dartboard of radius 9 inches. Let X1, X2, X3

Question:

Alfredo, Barbara, and Cathy throw darts at a dartboard of radius 9 inches. Let X1, X2, X3 denote the distance of Alfredo, Barbara, and Cathy's darts (respectively) from the center of the board. Thus, X(1) (the first order statistic) is the minimum distance from the center to any of the darts; X(3) is the distance to the farthest dart; and X(1) is the distance to the middle of the three darts with respect to the origin.
a. Find the density of X(2)
b. Check that fx(2)(x2) is a density, i.e., check that