A box contains 100 bulbs 20 of which are defective. 10 bulbs are selected for inspection. Find the probability that: i. all 10 are defective ii. all 10 are good ii. at least one is defective iv. none is defective.

Explanation

To solve the problem step by step, we will calculate the probabilities for each of the four parts of the question.

### Given:
- Total bulbs = 100
- Defective bulbs = 20
- Good (non-defective) bulbs = 100 - 20 = 80
- Bulbs selected for inspection = 10

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