. Find the mean and standard deviation of the following probability distribution:

Question

x 1 2 3
P(x) 0.4 0.25 0.35


Please show all of your work.

Answer 1

To find the mean:
SUM [x * P(x)]

Multiply each x by its respective probability P(x). Add together for a total. This will be your mean.

To find variance:
SUM [x^2 * P(x)] - mean^2

Square each x. Multiply each squared x by its respective probability P(x). Add together for a total. Square the mean. Subtract the squared mean from the total. This will be your variance.

To find standard deviation:
Take the square root of the variance.

Hopefully, this information will help you with problems of this type.