Question
How many four-letter words without repetition having
exactly two vowels can be formed by using the letters of the word "READING"?Solution
"READING" word has 4 consonants and 3 vowels.
Number of ways in which the four letters can be selected = 3C2 × 4C2 = 3 × 6 = 18
Now, these 4 letters can be arranged within the word in 4!=24 ways
So, the total number of words formed =18 × 24 = 432
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