Three machinesE1, E2 and E3 in a certain factory producing electric bulbs, produce 50%, 25% and 25% respectively, of the total daily output of electric bulbs. It is known that 4% of the bulbs produced by each of machines E1 and E2 are defective and that 5% of those produced by machine E3are defective. If one bulb is picked up at random from a day’s production, calculate the probability that it is defective.

Explanation

To find the probability that a randomly selected bulb from the production is defective, we can follow these steps:

### Step 1: Define the probabilities of selecting a bulb from each machine.
- Let \( P(E_1) \) be the probability that a bulb is produced by machine E1.
- Let \( P(E_2) \) be the probability that a bulb is produced by machine E2.
- Let \( P(E_3) \) be the probability that a bulb is produced by machine E3.

From the problem:
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