# TI-83 Discrete Random Variables

### TI-83 Discrete Random Variables

Suppose that x ( L

1

) is the number of pets owned by a family and P(x) ( L ) is the corresponding probability.

2

This represents a discrete probability distribution. Enter it as seen on the right.

Mean of a Discrete Probability Distribution

The mean is calculated by

    x

P

  

. Therefore, highlight L and enter

3

L

1

* L

2

as seen to the right.

Pressing ENTER will perform the calculation as can be seen here.

Now to calculate the mean we must sum the values in

L . Press 2

3 nd QUIT to go back to the home screen.

Now press 2 nd LIST and you should see the following display.

Key over to MATH and down to 5: sum( as seen here and press ENTER .

Enclose L in parentheses and press ENTER . This

3 gives you the mean of the Discrete Probability

Distribution.

Standard Deviation of a Discrete Probability Distribution

Use

    x

2 

P

 

2 to calculate the standard deviation. Begin by creating L with

4

L

1

2 to the right.

* L

2

as seen

After pressing ENTER L

4

will appear as follows.

Go back to the home screen and enter the command seen in the window to the right. Press ENTER and you will get the standard deviation.