Malik randomly picked two numbers from 1 to 9 (including 1 and 9). The same number could be picked more than once. The first of the two numbers he picks is odd and less than 5. What is the probability that the sum of the two numbers Malik picks is less than 5, given that the first number is odd and less than 5?
The first number chosen is either a 1 or a 3.(with a probability of 1/2 each).
If the first number chosen were a 1, the second number could either be a 1, 2, or 3 (with a probability of 3/9).
If the first number chosen were a 3, the second number would have to be a 1 (with a probability of 1/9).
Total probability is: (1/2) x (1/3) + (1/2) x (1/9) = .... the answer.