Question

Cindy has 6 identical pink candies and 8 identical green candies. Find the number of ways that Cindy can line up her candies in a row, so that there are exactly four places where a pink candy is next to a green candy. One example is $PPGGGPPPGGGGGP.$

Answer 1

175 ways

Explanation:

Form a partition into 2 or 3 parts and the number of ways.

Pink candies

[1,5](2) , [2,4](2) , [3,3](1) , [1,4](3), [1,2,3](6) , [2,2,2](1)

Green candies

[1,7](2) , [2,6](2) , [3,5](2) , [4,4](1) , [1,1,6](3) , [1,2,5](6) , [1,3,4](6) , ,[2,2,4](3) , [2,3,3](3)

Number of ways will be:

(2+2+1) (2+6+6+3+3) + (3+6+1)(2+2+2+1)

Number of ways =( 5×21) + (10×7) = 175ways