邏輯上有區別嗎？

假設

(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%.