There are unlimited number of identical balls of four different colours. How many arrangements of at most 8 balls in a row can be made by using them?
To try more such problems click here .
This section requires Javascript.
You are seeing this because something didn't load right. We suggest you, (a) try
refreshing the page, (b) enabling javascript if it is disabled on your browser and,
finally, (c)
loading the
non-javascript version of this page
. We're sorry about the hassle.
Split the problem into cases. The cases would be 1 ball in a row, 2 balls in a row, 3 balls in a row, and so on. There are 4 possible colors for each ball in the row. Therefore, there are 4 ways for the 1 ball in a row, 4x4 or 16 ways for the 2 balls in a row, 4x4x4 ways or 64 ways for the 3 balls in a row, and so on. Therefore, there are a total of 4+16+64+256+1024+4096+16384+65536=87380 ways.
I got the final result as following, the answer is a = 1 ∑ 8 ( ∑ b = 1 4 ( 4 b ) ( a 1 ! a 2 ! a 3 ! a 4 ! a ! ) ) , where b ⩽ a ,
a 1 + a 2 + a 3 + a 4 = a ,
and i ⩽ b , for a i .
Unfortunately, I cannot express it to be a more explicit form. I, however, obtained the answer as 8 7 3 8 0 which equal 1 − 4 4 ( 1 − 4 8 ) .
PS. I'm not sure whether the answer should be 87381 since we are considering arrangements of at most 8 balls in a row, is zero-ball arrangement in?
4+4^2+4^3+4^4+4^5+4^6+4^7+4^8=87380.
87381 was one of the numbers I tried too. As a matter of fact, the accepted answer is probably wrong because there is no such thing as one ball in a row, is there? In other words, the minimum number of balls should be two. But of course I'm splitting hairs.
Problem Loading...
Note Loading...
Set Loading...
4+4^2+4^3+4^4+4^5+4^6+4^7+4^8=87380.