Posted by Maureen on Monday, May 6, 2013 at 5:38am.
A firm manufactures light bulbs and those that come out of the assembly line are either defective or good. Every five bulbs that come out, 1 is defective. If 3 bulbs are selected at random, what is the probability that:
(i) All 3 are defective
(ii) All 3 are good
(iii) The first selected is defective
(iv) 1 defective and 2 good
(v) 2 defective and 1 good
(vi) At most 2 are good

Math  PsyDAG, Monday, May 6, 2013 at 1:38pm
If the events are independent, the probability of both/all events occurring is determined by multiplying the probabilities of the individual events.
1. (1/5)^3 = ?
2. (4/5)^3 = ?
3. 1/5
4. 1/5 * 4/5 * 4/5 = ?
5. You do it, using similar process.
6. This is none good, one good or 2 good.
Eitheror probabilities are found by adding the individual probabilities.