18 Dec 2023

Posted on:

04 Feb 2022

0

# 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

Instructor
Posted on:

07 Feb 2022

0

Hey,

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:

Therefore:

Hope this helps!

Kind regards,
365 Hristina

Posted on:

09 Feb 2022

0

Thank you, Hristina.

Posted on:

14 Mar 2022

0

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?

Instructor
Posted on:

15 Mar 2022

1

Hi Aaron,
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.

Best,
365 Eli

Instructor
Posted on:

16 Mar 2022

1

Dear all,

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

Kind regards,
365 Hristina

Posted on:

18 Mar 2022

0

Thanks both :D

Posted on:

18 Mar 2022

0

My only note is that it may need to be added to the 'Combinations With Repetition' page too, especially as this is what the question requires

Posted on:

03 Dec 2023

0

A more involved explanation (than just a mention on page 10) of the notation would be useful. The way it is used in the exam question does not make sense to me so I feel like I'm missing something.

Posted on:

15 Dec 2023

0

Same issue. I think there is an error with the way the question 6 was solved. Please kindly explain better

Instructor
Posted on:

18 Dec 2023

0

Hey Zainab,

Thank you for reaching out.

Could you please elaborate? What is the error you encountered?

Kind regards,

365 Hristina