prob stats

Question

Suppose you just received a shipment of fifteen televisions. Two of the televisions are defective. If two televisions are randomly? selected, compute the probability that both televisions work. What is the probability at least one of the two televisions does not? work?

Answer 1

P(Computer works) = 13/15

P(Doesn't work) = 2/15

 

We can solve with the binomial distribution.

 

1) P(2 computers work | 2 selected) = 2C2 * (13/15)^2 * (2/15)^0 = .751

 

2) P(at least 1 works | 2 selected) => which is really 1 - the probability that none work

 

1 - [2C0 * (13/15)^0 * (2/15)^2] = 1 - .018 = .982