How many bit strings of length 10 contain at least three 1s and at least three 0s?
My Approach:->
using product rule
There are 3 subtask following
(filling 3 ones in 10 places) =
(filling 3 zeros in remaing 7 places) =
(filling remaining 4 places) =
So,total number of bit string = ** which is greater than (total number of string).
Now , i want to know what is wrong in my apporach. please explain..