John draws a regular five pointed star in the sand, and at each of the 5 outward-pointing points and 5 inward-pointing points he places one of ten different sea shells. How many ways can he place the shells, if reflections and rotations of an arrangement are considered equivalent?

Any help is greatly appreciated

Memes4Life132 Jul 20, 2018

#1**+1 **

We can "anchor" any shell at either an outward-pointing or inward-pointing point

And for each of these, we have 9! ways to place the other shells

So....the total arrangements are 2 * 9! = 725760 arrangements

CPhill Jul 20, 2018

#2

#3**0 **

Where do you go to school?

Wherever it is, it’s fuckedup. The school doesn’t learn you math or grammar

The correct way to write this is, “The answer, which you have given, is incorrect.”

If you are going to write like this, you should use a quill. If don’t have a quill then just write

"You fuckedup the answer!"

Everyone understands that and no one will criticize your grammar.

BTW the answer is (4!)^{2}

The rotations are independent.

Guest Jul 21, 2018

edited by
Guest
Jul 21, 2018