6 couples decided to form a committee of four members, the number of different committees that can be formed in which no couple finds place is

Out of 9 consonants and 4 vowels, how many words of 4 consonants and 3 vowels can be formed?

The sum of all the numbers of four different digits that can be made using the digits 0, 1, 2 and 3 is

There are 50 intermediate stations on a railway line from one terminus to another. The number of ways a train can stop at 3 of these intermediate stations if no two of these stopping stations are to be consecutive, are