This applet simulates a probability tree diagram. Step 1: Click inside the appropriate box on the desired level to build the tree. Step 2: Click on "Set Probabilities" at the top. Step 3. When you enter the respective probabilities, you must hit the ENTER key after each one. Step 4: Once all of the probabilities have been set (they should be blue), click "Final Tree" Step 5: Click "Simulation".