Suppose you just received a shipment of 11 televisions 4 of

Suppose you just received a shipment of 11 televisions , 4 of the televisions are defective. If two televions are randomly selected, compute the probability that both televisions work. What is the probability at least one of the two televisions does not work?

Solution

There are 11C2 ways to choose 2 TVs.

There are 7C2 ways to choose Tvs that work.

Thus,

P(both work) = 7C2 / 11C2 = 0.381818182 [answer]

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P(at least one work) = 1 - P(both do not work)

There are 4C2 ways to choose TV\'s that do not work.

Thus,

P(both do not work) = 4C2 / 11C2 = 0.109090909

Thusm

P(at least one work) = 0.890909091 [answer]