Need help with explaination of Permutation Question (1 Viewer)

[MONKEYjulz]

Twelve differently coloured beads are arranged around a necklace. How many different arrangements are possible?

Is the working out: 11! / 2!
If it is why?

thanks

 

[clintmyster]

Twelve differently coloured beads are arranged around a necklace. How many different arrangements are possible?

Is the working out: 11! / 2!
If it is why?

thanks

I'd have thought it'd just have been (n-1)! so it'd be 11!

 

[Timothy.Siu]

its the same upside down

 

[jet]

its the same upside down

Exactly. It should be 11!/2, because you can flip the bracelet over and it can be symmetrical. I think its a tad stupid, and so did my old maths teacher, but oh well.

 

[MONKEYjulz]

Exactly. It should be 11!/2, because you can flip the bracelet over and it can be symmetrical. I think its a tad stupid, and so did my old maths teacher, but oh well.

If you can flip it over, then wouldn't circles be 11!/2 as well? This bracelet/necklace concept is ghai

 

[jet]

But, it would be illogical to flip a group of people or a table over, thus the reason why.

 

[clintmyster]

But, it would be illogical to flip a group of people or a table over, thus the reason why.

Oh my what a stupid mistake I made. I remember seeing a question like this in cambridge once and I was like screw that will never see it again and now I see it again haha

 

[khorne]

why is 11!/2 illogical? You can wear it on one side, and then flip it around and have a new necklace from the same old one...

 

[jet]

why is 11!/2 illogical? You can wear it on one side, and then flip it around and have a new necklace from the same old one...

What I mean was, it is illogical for tables of people etc (which is the usual application of these sorts of problems). That is the reason why we dont do those sorts of problems then divide by two, but we do in the case of bracelets etc.