Question 173396
From the ski lodge example, suppose that the probability of breaking your leg is 0.20. (Therefore the probability of not breaking your leg is (1 – 0.20) = 0.80.) 
What is the probability that exactly 2 out of 5 people will break their leg? 
n = 5, x = 2, p = .2, q = .8.
P(x=2) = 5C2(0.2)^2*(0.8)^3 = 10*0.04*0.512 = 0.2048
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What is the probability that less than 2 out of 5 people will break their leg?
P(x= 0 or 1) = 5C0(0.2)^0*(0.8)^5 + 5C1(0.2)^1*(0.8)^4 = 0.73728...
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Cheers,
Stan H.