Out of 7 consonants and 4 vowels , how many words of 3 consonants and 2 vowels can be formed ?
In how many ways can 21 books on English and 19 books on Hindi be pleaced in a row on a shelf so hat two books on Hindi may not be together ?
How many 3-digit number can be formed from the digits 2, 3, 5, 6, 7 and 9 , which are divisible by 5 and none of the digits is repeated ?
A box contains 2 whits balls , 3 black balls and 4 red ball . In how many ways can 3 balls be drawn from the box , if at least one black ball is to be included in he draw ?
In a group of 6 boys and 4 girls , four children are to be selected . In how many different ways can they be selected such that at least one boy should be there ?