How many different distinguishable horizontal arrangements of 7 identically shaped balls are there if 2 are blue, 3 are red, and 2 are yellow?
1 Answer
Sep 30, 2016
If the balls were all different (B1,B2,R1,R2,R3,Y1,Y2) we have:
Explanation:
But B1-B2 willl look the same as B2-B1, so we have to divide by
For the same reason we have to divide by
The red balls may be in
Summary :