概率的问题总是想不明白。。求问这题思路:
The probability that event A will occur is 0.5,The probability that event B will occur is 0.4,The probability that event A or B will occur is 0.8
A:Probability that A and B both occur
B:0.1
答案是相等。
我的思路是画韦恩图。A的概率是0.5,B的概率是0.4,那么0.4+0.5-2(A&B both occur)=0.8(A or B occur),所以算出来A&B both occur是0.05.
可是答案是0.1,所以我想是不是A&B both occur不要乘2,就只减去一个A&B both occur就好了,这样算出来A&B both occur就是0.1了。可是AB相交的话0.4+0.5的值不是算了两遍A&B both occur吗。。。所以就想不明白了。。。有没有大神给解释下