Question 1171634:  consider a binomial random variable X with n=5 and p=0.40 
a. Find the probability distribution of X 
b. Find P(X<3) 
C. Find P(2<=X<=4) 
d. Find the mean and the variance of X 
 Answer by Boreal(15235)      (Show Source): 
You can  put this solution on YOUR website! mean is 5*0.4 or 2 
variance is 2*0.6 or 1.2 
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probability x=0 is 0.6^5=0.07776 
probability x=1 is 5*0.4*0.6^4=0.2592 
for x=2 is 5C2*0.4^2*0.6^3=0.3456 
for x=3 it is 5C3*0.4^3*0.6^2=0.2304 
for x=4 it is 5*0.4^4*0.6=0.0768 
for x=5 it is 0.4^5=0.01024
 
for x<3, add the probabilities of x=0,1,2 
for 2 < x < 4, add the probabilities of x=2,3, 4 
 
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