In how many ways can the letters of the word "SCHOOL" be arranged such that no two vowels appear together?
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In how many ways can the letters of the word "SCHOOL" be arranged such that no two vowels appear together?
240
210
340
360
SCHOOL has 6 letters: S, C, H, O, O, L. Consonants: S, C, H, L (4). Vowels: O, O (2). Arrange consonants: 4! = 24. Spaces for vowels: _ S _ C _ H _ L _. 5 spaces for 2 vowels. Arrangements = 24 * 5P2 / 2! = 24 * 10 = 240.
The word SCHOOL has 6 letters with O repeated twice, meaning the 4 consonants can be arranged in 4! / 2! = 12 distinct ways. Arranging the 4 consonants creates 5 available gaps (including the ends) to place the 2 vowels so they do not touch; the vowels can be placed in these gaps in 5P2 = 20 ways. Multiplying the consonant arrangements by the vowel placements gives 12 multiplied by 20, which equals 240 ways.