# How to Simulate Picking Marbles on the TI-84 Plus

The Probability Simulation application on the TI-84 Plus can simulate picking one marble at a time from an urn that contains from two to five different types (colors) of marbles.

You even get to specify how many marbles of each type are in the urn and you get to tell the application whether or not a marble picked from the urn is placed back in the urn before the next selection is made. The application keeps track of the type of marble picked from the urn.

The data from the repeatedly picking marbles can be displayed in a histogram or in a table. The application even gives you the option of saving you data so that you can, if you choose, statistically analyze it at a later time.

## How to pick marbles in Probability Simulation

To pick marbles from an urn, follow these steps:

Start the Probability Simulation application and press [3] to select the Pick Marbles option in the Main menu.

You see the Pick Marbles Home screen, as illustrated in the first image.

To use the Pick Marbles simulator after using another simulator, repeatedly press [Y=] until you see the Main menu (second picture) and then press [3] to select the Pick Marbles simulator.

Press [ZOOM] to display the Settings editor. Change the settings in Settings editor, as appropriate.

You see a screen similar to the Toss Coins simulator’s Settings editor.

The

**Types**option lets you tell the application how many different types (colors) of marbles in the urn. The urn can contain from two to five different kinds of marbles. The**Replace**option lets you tell the simulator if a marble is put back in the urn (**Yes**) or not (**No**) before another marble is picked from the urn.To enter a number in

**Trial Set**, use the arrow keys to place the cursor on the existing number, use the keypad to enter a new positive integer, and then press**[ENTER]**. To select other options, use the arrow keys to place the cursor on the option, and then press**[ENTER]**to select the option.Don’t forget the

**Update**option. The down arrow in the lower-right corner of the screen indicates that you should repeatedly pressto reach this option.

Press [WINDOW] to display the Advanced Settings editor. Enter the number of each type of marble in the urn.

The Advanced Settings editor is illustrated in the second picture. To change the number of marbles of a certain type, use the arrow keys to place the cursor on the number appearing next to that type, use the keypad to enter a new positive integer, and then press

**[ENTER]**.Press [GRAPH] to say OK to the weights in the Advanced Settings editor. Press [GRAPH] again to say OK to the settings in the Settings editor.

You see the Pick Marbles Home screen. If you set the

**Replace**option to**Yes**, the letter R appears in the upper-left corner of the screen.Press [WINDOW] to pick marbles.

The histogram appears on the screen. If in Step 2 you set

**Trial Set**to 1, then only one bar appears in the histogram.Continue picking marbles.

If in Step 2 you set

**Trial Set**to a number greater than one, press**[WINDOW]**to pick more marbles.Press

**[WINDOW]**to pick one more marble,**[ZOOM]**to pick ten more marbles, or**[TRACE]**to pick 50 more marbles.If in Step 2 you set

**Replace**to**No**, then the urn could eventually run out of marbles. When this happens, the simulator displays the “no more marbles” message and will, of course, not allow you to pick any more marbles from the urn. To pick more marbles after seeing this message, start a new simulation of picking marbles by following Steps 2 through 6. In Step 2 if you don’t see the**SET**command, press**[Y=]**to get back to the Pick Marbles simulator’s Home screen.

## How to read the Pick Marbles graph and table

The cumulative data from picking marbles is stored in both a histogram and a table. The histogram, by default, is displayed on the screen without any values on the *y*-axis. Here are some specifics about the Pick Marbles simulator’s histogram and table:

**Pick Marbles histogram:**Each bar in the histogram records the data for each type of marble in the urn.**Pick Marbles table:**The first column displays the number of the pick and the second column shows what type of marble was picked.