44 We are given n (n>5) points in space, no three of which lie on the same straight line. Let 2 be the family of planes defined by any three of these points. Suppose that the points are situated in a way that no four of them are coplanar, and no two planes of 2 are parallel. From the set of the lines of the intersections of the planes of 2, a line is selected at random. What is the probability that it passes through none of the n points?

Hint: For 0, 1, 2, let A, be the set of all lines of the intersec- tions that are determined by planes having i of the given n points in common. If A, denotes the number of elements of A, the answer is Aol/ (Aol+|A|+|A).