2. If Xi are iid exponential with mean A, show that S,- with shape parameter r and mean r X 3. Show that -+- x r is Gamma distributed IP(X > r) = IP(X > y) for X being Exponentially distributed and Geometrically distributed on the positive integers. 2. If Xi are iid exponential with mean A, show that S,- with shape parameter r and mean r X 3. Show that -+- x r is Gamma distributed IP(X > r) = IP(X > y) for X being Exponentially distributed and Geometrically distributed on the positive integers.