there are 4 red chips and 2 blue ones . when arranged in a row , they form a certain color pattern , for example rbrrb . how many color patterns ?
using anagram method : 6 _ 5 _ 4 _ 3 _ 2 _ 1 r _ r _ r _ r _ b _ b so . . 6 ! / number of repeated letters ( 4 ! ) ( 2 ! ) = 5 ans : d
multiply(factorial(4), factorial(2))