Question 1066534: (1)A box contains 4 red and 5 white flowers. A random sample of 6 flowers is drawn without replacement from the box. Find the probability that the sample contains 3 red flowers.
(2)Suppose the number of defective screws produced by a machine per day follows Poisson distribution with parameter 2. What is the probability that, out of the total production of the day, there are at least one defective screw?
Answer by Boreal(15235)   (Show Source):
You can put this solution on YOUR website! The first is 4C3*5C3 all divided by 9C6, the number of ways of choosing the 6 flowers.
=4*10/84=40/84
That is 10/21
The other possibilities are 2 red, 4 white, which is 30/84, 1 red and 5 white, 4 ways, and 4 red 2 white, which is 10 ways.
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at least 1 is the same as 1-none.
probability of none is e^(-2)*2^0/0! or e^(-2)=0.1353
1- that probability is 0.8647.
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