Question

Find the number of four letter word that can be formed from the letter of the word $HISTORY$ .(each letter to be used atmost once)
How many of them begin with a vowel?

Answer 1

total number of different types of letters = $7$

we have to make a $4$ letter word that begins with a vowel ,

no. of vowels = 2

no. of ways in which first letter can be filled = 2

no. of ways it can be done = $2\times 6\times 5\times 4$

=$12\times 20=240ways$