Rachel C.

asked • 03/28/21

Probability - When to use Combination v. Permutation

Could someone clarify if a permutation is supposed to be used to solve a problem with no replacement included, using the following question as an example to explain?


Jacob has 10 rap, 18 rock, 8 country, and 4 pop songs in his playlist. Two are selected at random. Find each probability:

A. P (2 pop) B. P(2 country C. P(1 rap, 1 rock) D. P(not rock)


(sorry for the awkward phrasing)


1 Expert Answer

By:

Jon S. answered • 03/28/21

Tutor
5 (6)

Patient and Knowledgeable Math and English Tutor

Rachel C.

Hi, Thanks so much for the help! However, for part C. the answer key provided by my teacher states the correct answer is 3/26, which can be found using P(10,1)P(18,1)/P(40,2), which is what I was mainly confused about in my original post. I don't understand why a permutation (nPr) is used here when the order of the selected songs does not mater. Could you help clarify this?
Report

03/28/21

Still looking for help? Get the right answer, fast.

Ask a question for free

Get a free answer to a quick problem.
Most questions answered within 4 hours.

OR

Find an Online Tutor Now

Choose an expert and meet online. No packages or subscriptions, pay only for the time you need.