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March 3, 2015

March 3, 2015

Posted by **Mattie** on Wednesday, May 25, 2011 at 9:47am.

What is the probability?

- STATS -
**drwls**, Wednesday, May 25, 2011 at 10:20amYour question is worded in a confusing way. It sounds like the next 20 cars IN A ROW would have to be red. That would be a very low probability, (0.28)^20 = 8.8*10^-12, and the 30 cars seen after that would not matter.

Don't you mean that you want the probability that exactly 20 of the next 50 will be red?

That probability is

P(20) = (0.28)^20*(0.72)^30^50!/[30!*20!]

= 0.0217

The most likely number of red cars out of 50 would be 14. That probability is

P(14) = (0.28)^14*(0.72)^36* 50!/[14!*36!] = 0.1248

=

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