1. Find the coefficient of x^24 in (x^3+ x^4+ x^5+ x^6)^5.

2. Consider the problem of counting the ways to select 25 objects from 8 types with at least two of each type.

a) Model this problem as an integer-solution-of-equation-problem.

b) Model this problem as a certain coefficient of a generating function.

c) Solve this problem.

3. How many 6-digit decimal sequences are there with exactly r 3's ( for some r, 1 <= r <= 5)?

4. What is the probability that a 15-card subset out of the 52-card deck has exactly four three-of-a-kinds but no four-of-a-kind and no pairs?

5. How many arrangements of MATHEMATICAL are there in which ME appear together (TM immediately followed by E) but the ME is not immediately followed by an A (no MEA)?

6. How many arrangements of letters in ORIGINATING have ALL of the following properties:

(i) there are at least two letters between each I,

(ii) begins or ends with an I, and

(iii) the consonants are in alphabetical order.

7. You have 6 friends. How many ways are there to invite a different subset of two of these friends over for dinner on 4 successive nights?

(A friend might be invited more than once; just the subset of 2 friends must be different each night.)

1. Find the coefficient of x^26 in (x^2+x^3+x^4+x^5+x^6)^8.

2. Consider the problem of counting the ways to distribute 27 identical objects into 8 different boxes with at least three objects for each box.

a) Model this problem as an integer-solution-of-equation-problem.

b) Model this problem as a certain coefficient of a generating function.

c) Solve this problem.

3. How many arrangements of the 26 different letters of the alphabet (with no repeats) are there in which all the consonants appear before all the vowels (a,e,i,o,u)?

4. How many digit (0,1,2,3,4,5,6,7,8,9) sequences of length 9 are there that contain at least 4 odd digits (1.3.5.7.9) and at least 4 even digits (0,2,4,6,8)? (Repetition allowed.)

5. Find the probability that a 10-card hand (from a 52-card deck) has exactly 2 four-of-a-kinds (no 3-of-a-kinds and no pairs).

6. How many arrangements of the letters in ARITHMETIC have ALL of the following 3 properties:

(i) begins with an E

(ii) at least two letters between each I,

(iii) the consonants are in alphabetical order, and

(iv) the vowels are not in alphabetical order.

7. How many subsets of 3 distinct integers from 1, 2, 3, . . . , 90 are there whose sum of integers is divisible by 3?

1. Find the coefficient of x^23 in (x^3+x^4+x^5+x^6)^4.

2. Consider the problem of counting the ways to select 27 donuts from 5 types with at least three of each type.

a) Model this problem as an integer-solution-of-equation-problem.

b) Model this problem as a certain coefficient of a generating function.

c) Solve this problem.

3. How many arrangements of INSTRUCTIVE in which each T is followed by a vowel?

4. How many sequences of length 6 formed from the 26 letters without repetition are there where the vowels (a,e,i,o,u) may only appear in the first or/and last positions (possibly neither)?

5. Find the probability that a 13-card hand (from a 52-card deck) has exactly 3 three-of-a-kinds (no 4-of-a-kinds and no pairs).

6. How many arrangements of the letters in DISAPPEARANCES have ALL of the following properties:

(i) there are at least two letters between each A,

(ii) ends with an A, and

(iii) the consonants are not in alphabetical order.

7. How many ways are there to select 8 donuts from 6 types of donuts if at most 3 donuts are chosen from the first two types combined;

that is, at least 5 donuts chosen from the other four types. (Hint: break into cases)