What is the probability that four 'S' comes consecutively in the word 'MISSISSIPPI` when rearranged?

Explanation

There are `11` letters in the word 'MISSISSIPPI' which can be arranged in `11 !` ways.

Number of the letter S`=4`

Let us consider the four `S^{prime}` s in the given word as one letter.

As a result, when the four letters are combined, we have (SSSS) MIIIPPI. Eight letters can be arranged in a row in `8 !` ways.

Also, the four S's can be arranges in `4 !` ways.

Hence, required probability `=frac{8 ! times 4 !}{11 !}=frac{8 ! times 4 times 3 times 2}{11 times 10 times 9 times 8 !}=frac{4 times 3 times 2}{11 times 10 times 9}=frac{4}{165}`