Aflea of negligible size is trapped in a large, spherical, inflated beach ball with radius r. at this moment, it is equally likely to be at any point within the ball. let x be the distance of the flea from the center of the ball. using the fact that the volume of a sphere of radius r is 4tr /3, for x, find (a) cumulative distribution function f. ( the probability density function f. (c) expected value. d) . the variance.