Posted by **George** on Thursday, October 11, 2012 at 12:04pm.

Calculate the expected value and standard deviation of X, the number of on the job accidents:

Accidents 0,1 2 Probability .5, ?, .2

P(X=1) =

E(x) = µx =

Standard deviation =

- Stats -
**MathGuru**, Thursday, October 11, 2012 at 7:10pm
Note: Your ? value should be .3 because each probability will then add to 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 other problems of this type.

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