Question 619075
The probability that you will invest in a stock which appreciates, or is a “good” stock is 1 in 10. Find the probability that your 6th stock is your 3rd good stock? 
I dont know where to start. Please helpppp 
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Let "g" be good stock
Let "n" be not good stock
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Acceptable patterns: -,-,-,-,-,-
Last stock is "g".
There are 5C2 = 10 ways to place 2 other "g" stock in the 1st five.
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P(condition) = (10*g^2*n^3)*g = 10(0.1)^3*(0.9)^3 = 0.0081
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Cheers,
Stan H.