For any convex body K in
euclidean n-space denote by m(K) the mean value of the volume of a simplex with
vertices at n + 1 randomly selected points from K. It is shown that among all convex
bodies of given volume the mean value m(K) is minimal if and only if K is an
ellipsoid. Actually, a more general result is obtained which shows that the higher
order moments of the volume of a randomly selected simplex in a convex set have
similar minimal properties.