How many 5-letter \"words\" can be formed from the letters S-W-I-N-G if all the letters are different and the middle letter is I? Solution As the position of I is fixed only 4 letters will changethere positions. so probability of every letter of being in any of the remaining 4 positions is 4. so probability of forming 5 lettered words with I in fixed position = 4! = 4x3x2x1 = 24.