I have 5 marbles numbered 1 through 5 in a bag. Suppose I take out two different marbles at random. What is the expected value of the sum of the numbers on the marbles?
+118667 I have 5 marbles numbered 1 through 5 in a bag. Suppose I take out two different marbles at random. What is the expected value of the sum of the numbers on the marbles?
| Sum | 1 | 2 | 3 | 4 | 5 |
| 1 | X | X | X | X | X |
| 2 | 3 | X | X | X | X |
| 3 | 4 | 5 | X | X | X |
| 4 | 5 | 6 | 7 | X | X |
| 5 | 6 | 7 | 8 | 9 | X |
There are 10 choices so each one has a prob of 1/10=0.1
0.1( 3+4+5+5+6+7+6+7+8+9) = 6
