I have time for a couple of quick replies:
I have a couple of questions I would like help with.
1. In a permutation (nPr), is 'n' always the larger number?
Mr F says: . What happens if n < r ....?
For example, there are 5 students and 10 desks, how many permutations are there?
Mr F says: How many ways can you arrange 10 desks among 5 students ......? (10P5).
2. 9 people need to be seated. Henry must not sit with Wilson or Nancy. How many permutations will there be?
Mr F says: I assume in a row ....? Work out how many arrangements when Henry DOES sit with Wilson or Nancy. Subtact this from the number of arrangements without any restriction.
3. How many different ways can six people be seated at a round table?
Mr F says: You surely have a formula ....... 5!