1. Four different written driving tests are administered by a city. One of these tests is selected at random for each applicant for a drivers license. If a group of 2 women and 4 men apply, find the number of ways:

(a) exactly 3 of the 6 people will take the same test.

(b) the 2 women take the same test.

(c) all 4 men take different tests.

2. How many binary strings (strings of 0s and 1s) contain exactly five 0s and 14 1s if every 0 must be immediately followed by two 1s?

3. In how many ways can 6 men and 4 women sit down around a circular table

(a) with no restrictions?

(b) if women can not sit directly next to each other?

(c) if all 6 men must sit consecutively?

4. Consider passwords consisting of a string of 4 characters, each selected from (A,B,C,D,E, F,G)

(a) How many passwords contain at least one A if repetition of characters is not allowed? An example of such a password is BAGF.

(b) How many passwords contain at least one A if repetition of characters is allowed? An example of such a password is BAAF.

(c) How many passwords are there if consecutive characters can not be identical, but repetition of characters is allowed? An example of such a password is ABAF.

(d) How many passwords contain exactly two As if repetition is allowed?

5. Let A = (1, 2, 3, 4, 5, 6) and B = (1, 2, 3, 4, 5, 6, 7, 8). How many binary relations from A to B contain the ordered pair (2, 5) but do not include the ordered pair (3, 3)? How many of the binary relations that you counted are also functions?