Permutations And Combinations Question 375

Question: How many different words can be formed by jumbling the letters in the word MISSISSIOOI in which no two S are adjacent?

Options:

A) $ {{8.}^{6}}C_4{{.}^{7}}C_4 $

B) $ {{6.7.}^{8}}C_4 $

C) $ {{6.8.}^{7}}C_4. $

D) $ {{7.}^{6}}C_4{{.}^{8}}C_4 $

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Answer:

Correct Answer: D

Solution:

  • [d] First let us arrange M, I, I, I, I, P, P Which can be done in $ \frac{7!}{4!2!} $ ways Now 4 S can be kept at any of the ticked places in $ ^{8}C_4 $ ways so that no two S are adjacent. Total required ways $ ={{\frac{7!}{4!2!}}^{8}}C_4={{\frac{7!}{4!2!}}^{8}}C_4=7\times {{}^{6}}C_4\times {{}^{8}}C_4 $