We calculate the probability of from the reduced sample space The A B. formula to calculate P(A|B) is where P(B) is greater than 0. For example, suppose we toss one fair, die. The sample space S = {1, 2, 3, 4, 5, 6}. Let = face is 2 or 3 and = face is even (2, 4, 6). A B To calculate P(A|B), we count the number of outcomes 2 or 3 in the sample space B = {2, 4, 6}. Then we divide that by the number of outcomes in (and not B S). We get the same result by using the formula. Remember that has 6 S outcomes.
We calculate the probability of A from the reduced sample space B. The formula to calculate P(A|B) is where P(B) is greater than 0. For example, suppose we toss one fair, die. The sample space S = {1, 2, 3, 4, 5, 6}. Let A = face is 2 or 3 and B = face is even (2, 4, 6). To calculate P(A|B), we count the number of outcomes 2 or 3 in the sample space B = {2, 4, 6}. Then we divide that by the number of outcomes in B (and not S). We get the same result by using the formula. Remember that S has 6 outcomes.