statistics- binomial distibution

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I really need help answering this question!!

A large box contains a mixture of three different types of bolts, in equal numbers. Another box contains the nuts for the bolts. Each nut only fits a bolt of the same type. A nut and a bolt are chosen at random and checked to see if they match (that is, they are of the same type). The process is repeated 12 times.

Find the probability that more than four matches are obtained.

Posted: 11-05-11 16:25 by Evette

I think the binomial you have to use is X ~ B(12, 1/3)

then the probability is P(X>4)

or you can use 1-P(X <or equal to 4) which then using the tables will be 0.6315

so your answer is 0.3685

Posted: 18-05-11 12:29 by Nicola

thank you so much, this was very helpful 

Posted: 31-05-11 19:26 by Evette