Hi,
Below is a quick summary of P&C:
0. Permutation is Combination with order being
considered, since we see their connection in the following result:
nPr = nCr x r!,
from which we see the
multiplication principle of choosing, then ordering.
1. Addition principle (useful when there are several
mutually exclusive cases).
2. Multiplication principle (useful when there are
several actions to be taken in sequence).
3. Exclusion principle (useful when we have a case like
this:
number of ways w/o restriction -
number of ways in which two people are together
to find the number of ways in
which two people are separated).
4. Principle of applying the restriction
first (useful when we have a case like this:
first and last digit is odd,
in which we find the number
of ways for that first).
5. Principle of handling repetitions (which usually
involves division by the factorial of the number of identical
items).
6. P&C is closely related to the topic of probability
in the following generic way:
P(event A occuring) = (number of
ways in which event A can occur) / (number of ways without
restriction).
Thanks!
Cheers,
Wen Shih
Hi Dr Wee,
Thank you for your kind explanation. Once again, I apologise
here for misleading everybody.
On a side note, I am not a "he".
Cheers.