Let us assume a person climbing the stairs can take one stair or two stairs at a time. How many ways can this person climb a flight of eight stairs?

In a pack of 42 cards, 3 cards are chosen one after the other. Find the number of ways this can be done without replacement:

Let us assume a person climbing the stairs can take one stair or two stairs at a time. How many ways can this person climb a flight of eight stairs?

How many ways are there to assign 5 different jobs to 4 different employees if every employee is assigned at least 1 job?

There are three boxes. First box has 2 white, 3 black and 4 red balls. Second box has 3 white, 2 black and 2 red balls. Third box has 4 white, 1 black and 3 red balls. A box is chosen at random and 2 balls are drawn out of which 1 is write, and 1 is red. What is the probability that the ball balls came from first box?