How many different words, each containing 2 vowels and 3 consonants can be formed with 5 vowels and 17 consonants?
Given that we need to find the no. of words formed by 2 vowels and 3 consonants which were taken from 5 vowels and 17 consonants.
Let us find the no. of ways of choosing 2 vowels and 3 consonants and assume it to be N1.
⇒ N1 = (No. of ways of choosing 2 vowels from 5 vowels) × (No. of ways of choosing 3 consonants from 17 consonants)
⇒ N1 = (5C2) × (17C3)
We know that ,
And also n! = (n)(n – 1)......2.1
⇒
⇒
⇒
⇒ N1 = 10 × 680
⇒ N1 = 6800
Now we need to find the no. of words that can be formed by 2 vowels and 3 consonants.
Now we need to arrange the chosen 5 letters. Since every letter differs from other.
The arrangement is similar to that of arranging n people in n places which are n! ways to arrange. So, the total no. of words that can be formed is 5!.
Let us the total no. of words formed be N.
⇒ N = N1 × 5!
⇒ N = 6800 × 120
⇒ N = 816000
∴ The no. of words that can be formed containing 2 vowels and 3 consonants are 816000.