Another question about permutations (1 Viewer)

[goobi]

I'm really stuck with permutations which is the most difficult Extension 1 topic for me so yeah...
Okay so the question is:

Ten balls of identical size are placed side by side in a line. If 4 balls are read in colour, 3 are blue and 2 are green and 1 is white, in how many arrangements will there be a red ball at each end?

The answer is 1680 but I don't know how to get it.

Thanks for any help again!

 

[Mature Lamb]

Set 2 red balls, one at each end.

You will have 2 red balls, 3 blue balls, 2 green balls, and 1 white ball left to arrange in the middle.

 

[goobi]

Set 2 red balls, one at each end.

You will have 2 red balls, 3 blue balls, 2 green balls, and 1 white ball left to arrange in the middle.

So, do you think this solution is correct?
8!2! / 2!3!2!2!

 

[Mature Lamb]

So, do you think this solution is correct?
8!2! / 2!3!2!2!

Correct.

 

[ohexploitable]

put 2 red balls at ends, there is only 1 way to arrange them