假设
(a) probable means > 50%, e.g. more likely than not. and
(b) white girl using wechat is A, white gir notl using wechat is !A (not A)
statement 1. It is not probable that a white girl would use wechat. means !(A > 50%), i.e. A <= 50%
statement 2. It is probable that a white girl would not use wechat means !A > 50% i.e. A <=50%
compare to:
statement 3 It is not possible that a white girl would use wechat means A = 0%
statement 4 It is possible that a white girl would not use wechat means !A > 0% i.e. A < 100%.
