1. The integer '5' occurs once in the sequence of [1, 2, 3, 4, 5, 6, 7, 8, 9, 10], hence, the probability of it appearing is 1/10, or 10%.
2. Odd numbers are found in this sequence more than once. 1, 3, 5, 7, 9 are all odd numbers, and there are 5 of them. Hence the probability is 5/10, or 50%
3. A factor of 20 is any integer that can go into 20. These are 1, 2, 4, 5, 10. Once again, there are 5 of these in the sequence, hence the answer is 50%.
The answers are:
1. 10%
2. 50%
3. 50%
