
Mike D. answered 07/30/20
Effective, patient, empathic, math and science tutor
Arshiyanformation
There are 7 different consonants and 3 different vowels here.
So let's think about the letters where we have information.
We can choose the 2nd letter in 7 ways (as it must be a consonant).
Having chosen that there are 6 ways to choose the 3rd letter (7 consonants, one used already).
And there are 3 ways of choosing the last letter as it must be a vowel.
So we can choose the 2nd/3rd/last letter combination in 7 x 6 x 3 = 126 ways.
The other seven letters there is no restriction. We can choose the first from 7 letters (10 - 3 already used).
1st letter - we can choose from 7
4th letter - we can choose from 6
5th - choose from 5
6th - choose from 4
7th - choose from 3
8th - choose from 2
9th - choose from 1
So total ways of choosing letters = 126 x 7 x 6 x 5 x 4 x 3 x 2 x 1 = 126 x 7 ! = 635 040 ways
Mike
Arshiyan K.
THANK YOU you are amazing07/30/20