math
posted by linda .
15 tv were shipped 4 were defective if 2 tv's were random selected compute the possibility of both tv's working and the probability that at least one of the 2 tv does not work

If the events are independent, the probability of both/all events occurring is determined by multiplying the probabilities of the individual events.
11/15 * 11/15 = ?
That means one or both do not work.
One not work = 4/15 * 11/15 = ?
Both not work = 4/15 * 11/15 = ?
Eitheror probabilities are found by adding the individual probabilities.