Ten percent of the items produced by a machine are defective

Ten percent of the items produced by a machine are defective. Out of 15 items chosen at random, what is the probability that less than 3 items will be defective?

Solution

P(defective) = 0.10

= P(0 defetive) + P(1 def. ) + P( 2 def.)

= 15c0*(0.90)^15 + 15c1*0.1*(0.9)^14 + 15c2*(0.1)^2*(0.9)^13

= 0.816.....Answer

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