Evaluate the cumulative distribution function, F , for the given random variable, X , at specified values; also determine the requested probabilities. f ( x ) = ( 27/13 ) ( 1/3 ) x , x = 1 , 2 , 3 Give exact answers in form of fraction. F ( 1 ) = F ( 2 ) = F ( 3 ) = (a) P ( X 1.5 ) = (b) P ( X 3 ) = (c) P ( X > 2 ) = (d) P ( 1 < X 2 ) = .