What is the probability that for S's come consecutively in the word `MISSISSIPPI'?

$\frac{4}{165}$

The total number of arrangements of the letters of the word 'MISSISSIPPI' is

$\frac{11!}{4!4!2!}$

Considering 4 S's as one letter, there are 8 letters which can be arranged in arrow in ways $\frac{8!}{4!2!}$ ways.

∴ Number of ways in which 4 S's come together = $\frac{8!}{4!2!}$

Hence, required probability $=\frac{8!/4!2!}{11!/4!4!2!}=\frac{8!×4!}{11!}=\frac{4}{165}$