In: Statistics and Probability
Suppose we roll a fair dice thrice in such a way that the assumption of random sampling is satisfied. Let {X1;X2;X3} be the numbers coming up in the first three throws.
Let their sample average be X3= (1/3) * ((X1+X2+X3))
1) Write down the sampling distribution ofX3. To this end, you need to write down a table that contains all values that X3 can take on together with their probabilities.
2) What is the probability that X3 greater than equal to 5, given that the dice is fair?
1.
| X1 | X2 | X3 | ![]() |
| 1 | 1 | 1 | 1 |
| 1 | 1 | 2 | 1.33 |
| 1 | 1 | 3 | 1.67 |
| 1 | 1 | 4 | 2 |
| 1 | 1 | 5 | 2.33 |
| 1 | 1 | 6 | 2.67 |
| 1 | 2 | 1 | 1.33 |
| 1 | 2 | 2 | 1.67 |
| 1 | 2 | 3 | 2 |
| 1 | 2 | 4 | 2.33 |
| 1 | 2 | 5 | 2.67 |
| 1 | 2 | 6 | 3 |
| 1 | 3 | 1 | 1.67 |
| 1 | 3 | 2 | 2 |
| 1 | 3 | 3 | 2.33 |
| 1 | 3 | 4 | 2.67 |
| 1 | 3 | 5 | 3 |
| 1 | 3 | 6 | 3.33 |
| 1 | 4 | 1 | 2 |
| 1 | 4 | 2 | 2.33 |
| 1 | 4 | 3 | 2.67 |
| 1 | 4 | 4 | 3 |
| 1 | 4 | 5 | 3.33 |
| 1 | 4 | 6 | 3.67 |
| 1 | 5 | 1 | 2.33 |
| 1 | 5 | 2 | 2.67 |
| 1 | 5 | 3 | 3 |
| 1 | 5 | 4 | 3.33 |
| 1 | 5 | 5 | 3.67 |
| 1 | 5 | 6 | 4 |
| 1 | 6 | 1 | 2.67 |
| 1 | 6 | 2 | 3 |
| 1 | 6 | 3 | 3.33 |
| 1 | 6 | 4 | 3.67 |
| 1 | 6 | 5 | 4 |
| 1 | 6 | 6 | 4.33 |
| 2 | 1 | 1 | 1.33 |
| 2 | 1 | 2 | 1.67 |
| 2 | 1 | 3 | 2 |
| 2 | 1 | 4 | 2.33 |
| 2 | 1 | 5 | 2.67 |
| 2 | 1 | 6 | 3 |
| 2 | 2 | 1 | 1.67 |
| 2 | 2 | 2 | 2 |
| 2 | 2 | 3 | 2.33 |
| 2 | 2 | 4 | 2.67 |
| 2 | 2 | 5 | 3 |
| 2 | 2 | 6 | 3.33 |
| 2 | 3 | 1 | 2 |
| 2 | 3 | 2 | 2.33 |
| 2 | 3 | 3 | 2.67 |
| 2 | 3 | 4 | 3 |
| 2 | 3 | 5 | 3.33 |
| 2 | 3 | 6 | 3.67 |
| 2 | 4 | 1 | 2.33 |
| 2 | 4 | 2 | 2.67 |
| 2 | 4 | 3 | 3 |
| 2 | 4 | 4 | 3.33 |
| 2 | 4 | 5 | 3.67 |
| 2 | 4 | 6 | 4 |
| 2 | 5 | 1 | 2.67 |
| 2 | 5 | 2 | 3 |
| 2 | 5 | 3 | 3.33 |
| 2 | 5 | 4 | 3.67 |
| 2 | 5 | 5 | 4 |
| 2 | 5 | 6 | 4.33 |
| 2 | 6 | 1 | 3 |
| 2 | 6 | 2 | 3.33 |
| 2 | 6 | 3 | 3.67 |
| 2 | 6 | 4 | 4 |
| 2 | 6 | 5 | 4.33 |
| 2 | 6 | 6 | 4.67 |
| 3 | 1 | 1 | 1.67 |
| 3 | 1 | 2 | 2 |
| 3 | 1 | 3 | 2.33 |
| 3 | 1 | 4 | 2.67 |
| 3 | 1 | 5 | 3 |
| 3 | 1 | 6 | 3.33 |
| 3 | 2 | 1 | 2 |
| 3 | 2 | 2 | 2.33 |
| 3 | 2 | 3 | 2.67 |
| 3 | 2 | 4 | 3 |
| 3 | 2 | 5 | 3.33 |
| 3 | 2 | 6 | 3.67 |
| 3 | 3 | 1 | 2.33 |
| 3 | 3 | 2 | 2.67 |
| 3 | 3 | 3 | 3 |
| 3 | 3 | 4 | 3.33 |
| 3 | 3 | 5 | 3.67 |
| 3 | 3 | 6 | 4 |
| 3 | 4 | 1 | 2.67 |
| 3 | 4 | 2 | 3 |
| 3 | 4 | 3 | 3.33 |
| 3 | 4 | 4 | 3.67 |
| 3 | 4 | 5 | 4 |
| 3 | 4 | 6 | 4.33 |
| 3 | 5 | 1 | 3 |
| 3 | 5 | 2 | 3.33 |
| 3 | 5 | 3 | 3.67 |
| 3 | 5 | 4 | 4 |
| 3 | 5 | 5 | 4.33 |
| 3 | 5 | 6 | 4.67 |
| 3 | 6 | 1 | 3.33 |
| 3 | 6 | 2 | 3.67 |
| 3 | 6 | 3 | 4 |
| 3 | 6 | 4 | 4.33 |
| 3 | 6 | 5 | 4.67 |
| 3 | 6 | 6 | 5 |
| 4 | 1 | 1 | 2 |
| 4 | 1 | 2 | 2.33 |
| 4 | 1 | 3 | 2.67 |
| 4 | 1 | 4 | 3 |
| 4 | 1 | 5 | 3.33 |
| 4 | 1 | 6 | 3.67 |
| 4 | 2 | 1 | 2.33 |
| 4 | 2 | 2 | 2.67 |
| 4 | 2 | 3 | 3 |
| 4 | 2 | 4 | 3.33 |
| 4 | 2 | 5 | 3.67 |
| 4 | 2 | 6 | 4 |
| 4 | 3 | 1 | 2.67 |
| 4 | 3 | 2 | 3 |
| 4 | 3 | 3 | 3.33 |
| 4 | 3 | 4 | 3.67 |
| 4 | 3 | 5 | 4 |
| 4 | 3 | 6 | 4.33 |
| 4 | 4 | 1 | 3 |
| 4 | 4 | 2 | 3.33 |
| 4 | 4 | 3 | 3.67 |
| 4 | 4 | 4 | 4 |
| 4 | 4 | 5 | 4.33 |
| 4 | 4 | 6 | 4.67 |
| 4 | 5 | 1 | 3.33 |
| 4 | 5 | 2 | 3.67 |
| 4 | 5 | 3 | 4 |
| 4 | 5 | 4 | 4.33 |
| 4 | 5 | 5 | 4.67 |
| 4 | 5 | 6 | 5 |
| 4 | 6 | 1 | 3.67 |
| 4 | 6 | 2 | 4 |
| 4 | 6 | 3 | 4.33 |
| 4 | 6 | 4 | 4.67 |
| 4 | 6 | 5 | 5 |
| 4 | 6 | 6 | 5.33 |
| 5 | 1 | 1 | 2.33 |
| 5 | 1 | 2 | 2.67 |
| 5 | 1 | 3 | 3 |
| 5 | 1 | 4 | 3.33 |
| 5 | 1 | 5 | 3.67 |
| 5 | 1 | 6 | 4 |
| 5 | 2 | 1 | 2.67 |
| 5 | 2 | 2 | 3 |
| 5 | 2 | 3 | 3.33 |
| 5 | 2 | 4 | 3.67 |
| 5 | 2 | 5 | 4 |
| 5 | 2 | 6 | 4.33 |
| 5 | 3 | 1 | 3 |
| 5 | 3 | 2 | 3.33 |
| 5 | 3 | 3 | 3.67 |
| 5 | 3 | 4 | 4 |
| 5 | 3 | 5 | 4.33 |
| 5 | 3 | 6 | 4.67 |
| 5 | 4 | 1 | 3.33 |
| 5 | 4 | 2 | 3.67 |
| 5 | 4 | 3 | 4 |
| 5 | 4 | 4 | 4.33 |
| 5 | 4 | 5 | 4.67 |
| 5 | 4 | 6 | 5 |
| 5 | 5 | 1 | 3.67 |
| 5 | 5 | 2 | 4 |
| 5 | 5 | 3 | 4.33 |
| 5 | 5 | 4 | 4.67 |
| 5 | 5 | 5 | 5 |
| 5 | 5 | 6 | 5.33 |
| 5 | 6 | 1 | 4 |
| 5 | 6 | 2 | 4.33 |
| 5 | 6 | 3 | 4.67 |
| 5 | 6 | 4 | 5 |
| 5 | 6 | 5 | 5.33 |
| 5 | 6 | 6 | 5.67 |
| 6 | 1 | 1 | 2.67 |
| 6 | 1 | 2 | 3 |
| 6 | 1 | 3 | 3.33 |
| 6 | 1 | 4 | 3.67 |
| 6 | 1 | 5 | 4 |
| 6 | 1 | 6 | 4.33 |
| 6 | 2 | 1 | 3 |
| 6 | 2 | 2 | 3.33 |
| 6 | 2 | 3 | 3.67 |
| 6 | 2 | 4 | 4 |
| 6 | 2 | 5 | 4.33 |
| 6 | 2 | 6 | 4.67 |
| 6 | 3 | 1 | 3.33 |
| 6 | 3 | 2 | 3.67 |
| 6 | 3 | 3 | 4 |
| 6 | 3 | 4 | 4.33 |
| 6 | 3 | 5 | 4.67 |
| 6 | 3 | 6 | 5 |
| 6 | 4 | 1 | 3.67 |
| 6 | 4 | 2 | 4 |
| 6 | 4 | 3 | 4.33 |
| 6 | 4 | 4 | 4.67 |
| 6 | 4 | 5 | 5 |
| 6 | 4 | 6 | 5.33 |
| 6 | 5 | 1 | 4 |
| 6 | 5 | 2 | 4.33 |
| 6 | 5 | 3 | 4.67 |
| 6 | 5 | 4 | 5 |
| 6 | 5 | 5 | 5.33 |
| 6 | 5 | 6 | 5.67 |
| 6 | 6 | 1 | 4.33 |
| 6 | 6 | 2 | 4.67 |
| 6 | 6 | 3 | 5 |
| 6 | 6 | 4 | 5.33 |
| 6 | 6 | 5 | 5.67 |
| 6 | 6 | 6 | 6 |
![]() |
Frequency=f | ![]() |
| 1 | 1 | 0.0046 |
| 1.33 | 3 | 0.0139 |
| 1.67 | 6 | 0.0278 |
| 2 | 10 | 0.0463 |
| 2.33 | 15 | 0.0694 |
| 2.67 | 21 | 0.0972 |
| 3 | 25 | 0.1157 |
| 3.33 | 27 | 0.125 |
| 3.67 | 27 | 0.125 |
| 4 | 25 | 0.1157 |
| 4.33 | 21 | 0.0972 |
| 4.67 | 15 | 0.0694 |
| 5 | 10 | 0.0463 |
| 5.33 | 6 | 0.0278 |
| 5.67 | 3 | 0.0139 |
| 6 | 1 | 0.0046 |
2.
