10. Only multiply for the and problem.

13. A probability distribution shows all the possible outcomes (in this case, 2 through 12) and how likely each one is.

14. This is an and problem, so multiply the probabilities.

15. You are choosing two of the eight council members.

17. The number of possible answer sequences is five choose problems multiplied together, and this becomes the denominator for the probability that a random sequence is the correct one.

19. This is three choose problems multiplied together.

20. This is three choose problems multiplied together, or it could also be calculated as a single permutation.