单选题
There is a 30 percent probability of rain this afternoon. There is a
10 percent probability of having an umbrella if it rains. What is the chance of
it raining and having an umbrella?
A. 33%.
B.9%.
C. 3%.
【正确答案】
C
【答案解析】P(A) =0.30. P(B|A)=0.10. P(AB)=(0.30)(0.10)=0.03 or 3%.