[tex] P = \frac{m}{n} [/tex]

[tex] n = C_{146}^2 = \frac{146!}{2!\cdot (146 - 2)!} = \frac{146!}{2!\cdot 144!} = \frac{145\cdot 146}{2} = 145\cdot 73 [/tex]

[tex] m = 1\cdot C_{145}^1 = 145 [/tex]

[tex] P = \frac{m}{n} = \frac{145}{145\cdot 73} = \frac{1}{73} [/tex]