Resolved: The practice exam 1, number 6
Hi Victor, thanks for this course.
In the practice exam for combinatorics, question 6, you gave the answer as; Combination with repetition. But the formula you used isn't the right formula for combination with repetition. You used (n+p-1)!/p! instead of (n+p-1)!/(n-1)!p!. Please is there a reason for that? If yes, what reason? Or was it a mistake on your part? Thanks
Thank you for the question!
In the explanation of the exercise, Victor has made use of the 'n-choose-k' notation. It is defined in the following way:
Hope this helps!
In question 6, the notation has been used to sub in the 'p' and 'n' instead of the formula.
However, I believe only the formula has been taught and not the notation.... This was rather confusing until I looked it up... Might be worth a video or resource explaining this?
thanks for your suggestion! We'll be adding аn explanation to the course notes for this particular formula, as I believe you're right, the notation is somewhat confusing and requires a more thorough explanation. I'll notify you once the new version of the course notes are up.
The new version of the course notes is now up. We have included the definition of the binomial coefficient on page 10 in the following file:
probability > Section 1 > 1_Course Introduction > Course notes > Probability - Course notes.pdf