Final answer:
The probability of selecting a defective bulb is 2/5.
Step-by-step explanation:
To find the probability that the selected bulb will be defective, we need to consider the probabilities of selecting from each box and the probability of selecting a defective bulb from each box.
First, let's calculate the probability of selecting from box 1. The probability of rolling a 1 or a 2 on a fair die is 2/6 or 1/3. Therefore, the probability of selecting from box 1 is 1/3.
The probability of selecting a defective bulb from box 1 is 4/20 or 1/5.
Next, let's calculate the probability of selecting from box 2. The probability of rolling anything other than a 1 or a 2 is 4/6 or 2/3. Therefore, the probability of selecting from box 2 is 2/3.
The probability of selecting a defective bulb from box 2 is 1/2.
Now, we can calculate the overall probability of selecting a defective bulb. We need to sum the probabilities of selecting from each box multiplied by the probabilities of selecting a defective bulb from each box:
(1/3) * (1/5) + (2/3) * (1/2) = 1/15 + 2/6 = 1/15 + 1/3 = 1/15 + 5/15 = 6/15 = 2/5