The random variable x is the number of males with tinnitus (ringing ears) among four randomly ...

 
3.   The random variable x is the number of males with tinnitus (ringing ears) among four randomly selected males (based on data from the American Journal of Medicine). 
 
        
x    P(x)
0    0.674
1    0.280
2    0.044
3    0.003
4    0+
 
a.   Determine if the table above is or is not a probability distribution.  Check all conditions and show that they are satisfied or not satisfied.
 
 
b.   Find the mean of the probability distribution. Round your answer to the nearest tenth.       
 
 
 
 c.   Using your answer from part b and given that the standard deviation of the above probability distribution is