新 GRE 数学重要考点：Conditional各个击破新 GRE 数学重要考点，今日我为大家整理的是 Conditional 相关的内容。 Conditional Probability of event A conditioned on the fact that event B has happened is called the conditional probability and written as P(AIB). P(AIB)=Probability Both A and B happens/ Probability B happens. Example: A six-sided die with faces from 1 to 6 is rolled twice. What is the probability that the face 5 turned up on first try given that the sum of the two faces is 9? P(sum of faces is 9)=4/36=1/9. P(face 5 turns up on the first try and sum is 9)=(1/6)*(1/6)=1/36. P(face 5 turned up on first try given sum is 9)=(1/36)*(1/9)=1/4. Remember: If P(AIB)=P(A),then two events A and B are independent, that is occurrence of one does not influence the other
