Given work is MISSISSIPPI, which has 11 letters of which M-1, S-4, I-4, P-2.
∴ Total number of arrangements
To find : Number of permutations of the letters in which four I’s not come together.
First, we find number of permutations of the letters in which four I’s are kept together.
Now, we treat four P s together as single object this single object together with 7 remaining objects (letters) will account for 8 objects. These 8 objects in which there are four 5’s and two P’s
can be arranged in 8!/4!2! ways.
∴ Number of words in which I’s kept together.