Question
How many four-letter words without repetition having
exactly two vowels can be formed by using the letters of the word "TRIANGLE"?Solution
"TRIANGLE" has 5 consonants and 3 vowels.
Number of ways to select the letters = 3C2 Γ 5C2 = 3 Γ 10 = 30
Arrangements of 4 letters = 4! = 24
Total number of words formed = 30 Γ 24 = 720
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