Finding Binomial probability

neckbone40

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Jul 1, 2009
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In a certain college, 20% of the physiscs majors belong to ethnic minorities. If 10 students are selected at random from the physics majors, what is the probability that exactly 2 belongs to an ethnic minority?

Please explain the approach... I'm swimming in stats.

Neckbone40
 
\(\displaystyle P(X=2)=\binom{10}{2}(.2)^2(1-0.2)^{10-2}=\frac{10\cdot 9}{2\cdot 1}(.2)^2(0.8)^{8}\)
 
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