Out of 7 consonants and four vowels, the no of words of six letters, formed by taking four consonants and two vowels is (assume that each ordered group of letter is a word ):

Total given consonants = 7

Total given vowels = 4

No. of consonant to be selected = 4

No. of vowel to be selected = 2

No. of ways for selecting 4 consonants out of 7 = C(7, 4) = 35

No. of ways for selecting 2 consonants out of 4 = C(4, 2) = 6

No. of arrangement for 6 letters word = 6! = 720

Hence the total number of arrangement = 35×6×720 = 151200