Use Table 2W or software to find

(a) \(F(4 ; 7)\);

(b) \(f(4 ; 7)\);

(c) \(\sum_{k=6}^{19} f(k ; 8)\).

Number of radio messages 0 Observed frequencies Poisson probabilities Expected frequencies 3 0.010 4.0 18 22.4 1234567890122 15 0.046 18.4 47 0.107 42.8 76 0.163 65.2 68 0.187 74.8 74 0.173 69.2 46 0.132 52.8 39 0.087 34.8 15 0.050 20.0 9 0.025 10.0 5209 0.012 4.8 0.005 2.0 8.0 0.002 0.8 0.001 0.4 400 400.0