Question 1188062
.


1)    To find this questionable number,  subtract the sum of all other given values of  P(x)  from  1.



3)    to calculate the variance and standard deviation of probability distribution,  go to this web-site


https://www.calculator.net/standard-deviation-calculator.html


Find an online calculator there, along with the nice 

professional and educational descriptions of this notion and the formula.


Use it and get the answer on your own.