Among the 12 car navigators on display at a trade show 9 are

Among the 12 car navigators on display at a trade show, 9 are Garmin, and the others are Tomtom. If a person visiting the show randomly selects 4 navigators to test, what is the probability that 3 of them will be the Garmin navigators?

Solution

See,

probability = number of favourable outcomes / all possible outcomes

In this case all possible outcomes = selecting 4 cars from 12 cars which can be done in 12 C 4 ways..

=495 ways

and the favourable outcomes are 3 garmin car and 1 tom tom ..

Hence favourable outcomes = 9C3 *3C1

=252 ways

hence the required probability is 252/495 =0.509

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