3.7 ([2] 3-18) verify that the function is probability mass function, and determine the requested probabilities. f(x)=()*, x = 1,2,3. a) P[X ≤ 1]. b) P[X > 1]. c) P[2 < X < 6]. d) P[X ≤ 1 or X > 1]

Fig: 1