In: Statistics and Probability
1. There are two events A and B. We are given the probabilities:

The conditional probability is given using the formula:

Substituting the values in the formula, we get:

Next, we are to determine the probability:

This can be calculated using the formula:

Substituting the values in the formula, we get:

2. Three identical bulbs are arranged in parallel. Let the probability of either of them failing be p and the probability of each of them working be q and q = 1 - p.
Now, the system will operate when either of the bulbs glow. Let the three bulbs be A, B and C. Hence, the probability that the system will not operate is:

The probability of this will be:

Now we have the probability of either of them failing is:

Hence, the probability of each of them failing is:

Thus, we have:

Hence, the probability of each of the light bulbs to fail is p = 0.4309