Question 896160
Consider the following probability distribution. 
X= 5 7 8
 P(X=x) 0.4 0.1 0.5 
1. Find the expected value for the discrete random variable X
E(X) = 0.4*5 + 0.1*7 + 0.5*8 = 6.7

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 2. Find the varance of X.
var(X) = 1.4177^2 = 2.0099
 3. Find the standard deviation of X.
std(X) = 1.4177
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 4. Find P(X>=7)
P(X = 7 or 8) = 0.1+0.5 = 0.6
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Cheers,
Stan H.
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