If A and B are independent, then the formula we use to calculate P (A∩B) is simply: Independent Events: P (A∩B) = P (A) * P (B) If A and B are dependent, then the formula we use to calculate P (A∩B) is: Dependent Events: P (A∩B) = P (A) * P (B|A)

P (A∩B) formula for dependent events can be given based on the concept of conditional probability. In this case, the probability of A intersection B formulas will be: P (A∩B) = P (A|B)P (B) or P (A∩B) = P (B|A)P (A)

The symbol "∪" (union) means "or". i.e., P (A∪B) is the probability of happening of the event A or B. To find, P (A∪B), we have to count the sample points that are present in both A and B. So is P (A∪B) = P (A) + P (B)? No, because while counting the sample points from A and B, the sample points that are in A∩B are counted twice.

P (A∪B) =P (A)+P (B)−P (A∩B) or 0.6 = 1−P (¯A)+1−P (¯B)−0.2 or P (¯A)+P (¯B) = 2−0.2−0.6 =1.2.