The standard deviation for the given probability distribution is;
σₓ = $6
The image for the probability distribution is missing and so i have attached it.
We are given;
Expected Value which is the mean as;
µₓ = $6
Now, from the probability distribution table attached, we can find the mean (expected value) of a discrete random variable X from;
Variance(X) = (-12 - 6)²(0.1) + (8 - 6)²(0.9) = 36
Thus, standard deviation of the random X is;
σₓ = √36
σₓ = $6
Read more about probability distribution at; https://brainly.com/question/4630765