Question 1203844
<font color=black size=3>
X = net winnings
<table border = "1" cellpadding = "5"><tr><td>Color</td><td>X</td><td>P(X)</td></tr><tr><td>Gold</td><td>4</td><td>1/30</td></tr><tr><td>Silver</td><td>2</td><td>8/30</td></tr><tr><td>Black</td><td>-1</td><td>21/30</td></tr></table>


Form a new column in which we multiply each X and P(X) value.
<table border = "1" cellpadding = "5"><tr><td>Color</td><td>X</td><td>P(X)</td><td>X*P(X)</td></tr><tr><td>Gold</td><td>4</td><td>1/30</td><td>4/30</td></tr><tr><td>Silver</td><td>2</td><td>8/30</td><td>16/30</td></tr><tr><td>Black</td><td>-1</td><td>21/30</td><td>-21/30</td></tr></table>


Add up the results of that last column to get the expected value.
4/30 + 16/30 + (-21/30)
=(4+16-21)/30
=-1/30
=-0.03 approximately


-------------------------------------------
-------------------------------------------


Answer: <font color=red size=4>-0.03 dollars</font>
It means you should expect to lose 3 cents, on average, each time you play the game.
</font>