in an experiment involving toxic substance ,the probability that a white mouse will survive for 5 hours and the probabillity that a black mouse will survive after 5hours _________________
这道题不全,后面应该给出的是两种老鼠的存活率(横线上应填的是“are __ and __ , respectively”)
不过,结合3个选项,我反推回去了,白鼠的存活率是60%,黑鼠的存活率是80%
这样,由于是独立事件(“assuming independence”),所以答案分别为
a.0.6*0.8=0.48=48%,选c (两只老鼠都存活)
b.0.8*(1-0.6)=32%,选a (只有黑鼠存活)
c.(1-0.6)*(1-0.8)=8%,选d (两只老鼠都死亡)