Question 625941
.
The probabilities that a batch of 4 computers will contain 0,1,2,3, and 4 defective computers 
are 0.6274, 0.3102, 0.0575, 0.0047, and 0.0001, respectfully. Find the standard deviation for the probability distribution.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~



I took the trouble / (the job)  to add up all five of these given numbers and got  0.9999  as the sum.


There should have been a  '1'  here,  then it would have been correct.


But the way it is presented in the post,  it can only make you smile at how 

illiterate or inaccurate are those who create and disseminate such problems.



        So, my advise to the problem's creator is  THIS:


                - you either exclude this problem from the consideration, 

                  or edit it in a way to make it perfect, as a Math problem should be.