There are 10 rolls of film in a box and 3 are defective. two rolls are selected without replacement. what is the probability of selecting a defective roll followed by another defective roll?

Question

Mathematics

Arthur Dean

1 November, 20:21

There are 10 rolls of film in a box and 3 are defective. two rolls are selected without replacement. what is the probability of selecting a defective roll followed by another defective roll?

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Answers (1)

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Michelle Walsh · Answer 1

P (picking one defective) = 3/10

P (picking a 2nd defective) = 2/9

P (1 and 2 defective) = 3/10 x 2/9 = 6/90 = 0.066

Second method using combination:

³C₂ / ¹⁰C₂ = 1/15 = 0.066