Multiplication Law of Probability
The probability of the simultaneous occurrence of 2 or more independent events is the product of the individual probabilities.
For example, in tossing two coins
Probability of heads –in one coin = ½
Probability of heads-in another coin = ½
Thus, the probability of heads in both coins = (1/2)x (1/2) = ¼.
Example
If it is known that 30% and 35% pregnant women have hypertension and anaemia respectively, what is the probability that a pregnant woman has
(i) either hypertension or anaemia?
(ii) both hypertension and anaemia?
For (i): Applying addition law, we have the required probability as 0.30 + 0.35 = 0.65
For (ii): Applying multiplication law, we have the required probability as 0.30 x 0.35 = 0.105
