Permutations and Combinations
There are always letters between and ?
Correct Answer: Option(a)
Solution: There are letters in word . occurs twice .
Here, and are fixed. These and can interchange their position. Hence, and can be arranged in ways.
Since, and are fixed, there are letters left , where occurs twice .
From these letters, letters can be chosen in ways.
Now since, letters are between and , so these six letters can be considered as a single object (letter). These four letter (between and )can be arranged in ways.
Now, the remaining letters and 1 object i.e. total can be arranged in ways.
Hence, required number of ways