(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

1. A group of people contains 10 with blood group O, 5 with blood group A and 5 with blood group B. Give a formula for the probability that a random sample of size 6 will contain two people from each group.

2. An athlete conceals 2 performance enhancing drugs in a bottle containing 8 vitamin tablets. If three tablets are selected at random for testing what is the probability cheating will be detected?

2. Relevant equations

3. The attempt at a solution

To get the six people having two from each group would it be

(10/20)(9/19)(5/18)(4/17)(5/16)(4/15) and there are 6! ways this can be arranged so my answer would be

P = 6!(10/20)(9/19)(5/18)(4/17)(5/16)(4/15)

Is this correct?

For part 2, there is 10 tablets in total. We take a sample of 3 tablets.

I'm sure there's a fancier way of doing this but all I can think of is this

P(drugs detected) = P(1 drug found) + P(2 drugs found)

= 3!(2/10)(8/9)(7/8) + 3!(2/10)(1/9)(8/8)

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# Homework Help: Probability homework question help

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