Question

求计算一概率题,稍作解释算法：某售货员销售概率是1/20,他接下来可销售给3名顾客中2两顾客的几率?

Answer 1

回答：

C(3,2) x (1/20)^2 x [1 - (1/20)]^1

= 3 x 0.0025 x 0.95

= 0.007125

= 0.7125%