combinatorics

A pot contains two red balls and two blue balls. Two balls are drawn from this pot randomly without replacement. What is the probability that the two balls drawn have different col...

Five different books (P, Q, R, S, T) are to be arranged on a shelf. The books R and S are to be arranged first and second respectively from right side of the shelf. The number of d...

There are 3 Indians and 3 Chinese in a group of 6 people. How many subgroups of this group can we choose so that every subgroup has at least one Indian?

The number of 3 digit numbers such that the digit 1 is never to the immediate right of 2 is

A fair dice is tossed two times. The probability that the $$2$$ nd toss results in a value that is higher than the first toss is

The number of distinct Boolean expressions of 4 variables is