Statistics Examples
P(A)=0.1P(A)=0.1 , P(B)=0.13P(B)=0.13 , P(BgivenA)=0.13P(BgivenA)=0.13
Step 1
Two events are independent events when the occurrence of one does not affect the probability of the other. P(A|B)=P(A)P(A|B)=P(A) and P(B|A)=P(B)P(B|A)=P(B).
P(A|B)=P(A)P(A|B)=P(A)
P(B|A)=P(B)P(B|A)=P(B)
Step 2
P(B|A)P(B|A) should equal to P(B)P(B) because the occurrence of AA should not effect the probability of BB for independent events AA and BB. In this case, P(B|A)=P(B)=0.13P(B|A)=P(B)=0.13.
P(B|A)=P(B)=0.13P(B|A)=P(B)=0.13
Step 3
Step 3.1
Using the Bayes' rule, P(A|B)=P(B|A)P(A)P(B)P(A|B)=P(B|A)P(A)P(B).
P(A|B)=P(B|A)P(A)P(B)P(A|B)=P(B|A)P(A)P(B)
Step 3.2
Substitute the given values P(A)=0.1P(A)=0.1, P(B)=0.13P(B)=0.13, and P(B|A)=0.13P(B|A)=0.13 in Bayes' rule.
P(A|B)=(0.13)⋅(0.1)0.13P(A|B)=(0.13)⋅(0.1)0.13
Step 3.3
Cancel the common factor of 0.130.13.
Step 3.3.1
Cancel the common factor.
P(A|B)=0.13⋅0.10.13
Step 3.3.2
Divide 0.1 by 1.
P(A|B)=0.1
P(A|B)=0.1
P(A|B)=0.1
Step 4
P(A|B) should equal to P(A) because the occurrence of B should not effect the probability of A for independent events A and B. In this case, P(A|B)=P(A)=0.1.
P(A|B)=P(A)=0.1
Step 5
P(A|B)=P(A) and P(B|A)=P(B), which means that A and B are independent events.
A and B are independent events