
Mathematics: A Practical Odyssey
8th Edition
ISBN: 9781305104174
Author: David B. Johnson, Thomas A. Mowry
Publisher: Cengage Learning
expand_more
expand_more
format_list_bulleted
Concept explainers
Textbook Question
Chapter 2.4, Problem 48E
Given the set S={a, b, c, d}, answer the following.
a. | How many one-element subsets does S have? |
b. | How many two-element subsets does S have? |
c. | How many three-element subsets does S have? |
d. | How many four-element subsets does S have? |
e. | How many zero-element subsets does S have? |
f. | How many does subsets does S have? |
g. | If n(S)=k, how many subsets will S have? |
Expert Solution & Answer

Want to see the full answer?
Check out a sample textbook solution
Students have asked these similar questions
For each of the following functions, find the Taylor Series about the indicated center and
also determine the interval of convergence for the series.
1. f(x) = ex-2, c = 2
Π
==
2. f(x) = sin(x), c =
2
QUESTION 5. Show that if 0 ≤r≤n, then
r+2
r
r
(c) + (+³) + (+³) +- + (*) -(+)
n
n+
=
r
(1)...using induction on n.
(2) ...using a combinatorial proof.
Use a power series to approximate each of the following to within 3 decimal places:
1. arctan
2. In (1.01)
Chapter 2 Solutions
Mathematics: A Practical Odyssey
Ch. 2.1 - Prob. 1ECh. 2.1 - Suppose A={2,5,7,9,13,25,26}. a. Find n(A) b. True...Ch. 2.1 - Prob. 3ECh. 2.1 - Prob. 4ECh. 2.1 - Prob. 5ECh. 2.1 - Prob. 6ECh. 2.1 - Prob. 7ECh. 2.1 - Prob. 8ECh. 2.1 - Prob. 9ECh. 2.1 - Prob. 10E
Ch. 2.1 - Prob. 11ECh. 2.1 - Prob. 12ECh. 2.1 - Prob. 13ECh. 2.1 - Prob. 14ECh. 2.1 - Prob. 15ECh. 2.1 - Prob. 16ECh. 2.1 - Prob. 17ECh. 2.1 - Prob. 18ECh. 2.1 - Prob. 19ECh. 2.1 - Prob. 20ECh. 2.1 - Prob. 21ECh. 2.1 - Prob. 22ECh. 2.1 - Prob. 23ECh. 2.1 - Prob. 24ECh. 2.1 - Prob. 25ECh. 2.1 - Prob. 26ECh. 2.1 - Suppose n(U)=150, n(A)=37, and n(B)=84. a. If...Ch. 2.1 - Prob. 28ECh. 2.1 - Prob. 29ECh. 2.1 - Prob. 30ECh. 2.1 - Prob. 31ECh. 2.1 - Prob. 32ECh. 2.1 - Prob. 33ECh. 2.1 - Prob. 34ECh. 2.1 - Prob. 35ECh. 2.1 - Prob. 36ECh. 2.1 - Prob. 37ECh. 2.1 - Prob. 38ECh. 2.1 - Prob. 39ECh. 2.1 - Prob. 40ECh. 2.1 - Prob. 41ECh. 2.1 - Prob. 42ECh. 2.1 - Prob. 43ECh. 2.1 - Prob. 44ECh. 2.1 - Prob. 45ECh. 2.1 - Prob. 46ECh. 2.1 - Prob. 47ECh. 2.1 - Prob. 48ECh. 2.1 - Prob. 49ECh. 2.1 - Prob. 50ECh. 2.1 - Prob. 51ECh. 2.1 - Prob. 52ECh. 2.1 - Prob. 53ECh. 2.1 - Prove the Cardinal Number Rule for the Complement...Ch. 2.1 - Prob. 55ECh. 2.1 - Prob. 56ECh. 2.1 - Answer the following questions using complete...Ch. 2.1 - Prob. 58ECh. 2.1 - Prob. 59ECh. 2.1 - Prob. 60ECh. 2.1 - Prob. 61ECh. 2.1 - Prob. 62ECh. 2.1 - Prob. 63ECh. 2.1 - Prob. 64ECh. 2.1 - Prob. 65ECh. 2.1 - Prob. 66ECh. 2.1 - Prob. 67ECh. 2.1 - Prob. 68ECh. 2.1 - The following questions are modeled after those...Ch. 2.2 - A survey of 200 people yielded the following...Ch. 2.2 - A survey of 300 workers yielded the following...Ch. 2.2 - The records of 1,492 high school graduates were...Ch. 2.2 - A department store surveyed 428 shoppers, and the...Ch. 2.2 - In a survey, 674 adults were asked what television...Ch. 2.2 - A survey asked 816 college freshmen whether they...Ch. 2.2 - A local 4-H club surveyed its members, and the...Ch. 2.2 - A local anime fan club surveyed its members...Ch. 2.2 - A recent survey of w shoppers that is, n(U)=w...Ch. 2.2 - A recent transportation survey of w urban...Ch. 2.2 - A consumer survey was conducted to examine...Ch. 2.2 - In a recent survey of monetary donations made by...Ch. 2.2 - Recently, Lady Gaga, Arcade Fire, and Skrillex had...Ch. 2.2 - Dr. Hawk works in an allergy clinic, and his...Ch. 2.2 - When the member of the Eye and I photo club...Ch. 2.2 - After leaving the polls, many people are asked how...Ch. 2.2 - In a recent survey consumer were asked where they...Ch. 2.2 - A company that specializes in language tutorial...Ch. 2.2 - In a recent survey, people were asked which radio...Ch. 2.2 - In a recent health insurance survey, employee at...Ch. 2.2 - A survey of 136 pet owners yielded the following...Ch. 2.2 - An exit poll of 300 votes yielded the following...Ch. 2.2 - Prob. 23ECh. 2.2 - Prob. 24ECh. 2.2 - Prob. 25ECh. 2.2 - Prob. 26ECh. 2.2 - Prob. 27ECh. 2.2 - Prob. 28ECh. 2.2 - Prob. 29ECh. 2.2 - Prob. 30ECh. 2.2 - Prob. 31ECh. 2.2 - Prob. 32ECh. 2.2 - Using Venn diagrams, prove De Morgans law (AB)=AB.Ch. 2.2 - Prob. 34ECh. 2.2 - Use the data in Figure 2.34 to complete Exercise...Ch. 2.2 - Use the data in Figure 2.34 to complete Exercise...Ch. 2.2 - Prob. 37ECh. 2.2 - Prob. 38ECh. 2.2 - Use the data in Figure 2.34 to complete Exercise...Ch. 2.2 - Prob. 40ECh. 2.2 - If a person has type B blood, what blood types may...Ch. 2.2 - Prob. 42ECh. 2.2 - If a person has type O blood, what blood types may...Ch. 2.2 - Answer the following questions using complete...Ch. 2.2 - Prob. 45ECh. 2.2 - Prob. 46ECh. 2.2 - Prob. 47ECh. 2.2 - Prob. 48ECh. 2.2 - Exercises 4652 refer to the following: A nonprofit...Ch. 2.2 - Prob. 50ECh. 2.2 - Prob. 51ECh. 2.2 - Prob. 52ECh. 2.2 - Prob. 53ECh. 2.3 - Prob. 1ECh. 2.3 - Prob. 2ECh. 2.3 - Jamie has decided to buy either a Mega or a Better...Ch. 2.3 - Prob. 4ECh. 2.3 - If you buy three pairs of jeans, four sweaters,...Ch. 2.3 - A certain model of automobiles is available in six...Ch. 2.3 - To fulfill certain requirements for a degree, a...Ch. 2.3 - To fulfill a requirement for a literature class, a...Ch. 2.3 - A sporting goods store has fourteen lines of snow...Ch. 2.3 - An audio equipment store has ten different...Ch. 2.3 - A cafeteria offers a complete dinner that includes...Ch. 2.3 - A sandwich shop offers a U-Chooz special...Ch. 2.3 - How many different Social Security numbers are...Ch. 2.3 - To use an automated teller machine ATM, a customer...Ch. 2.3 - Every book published has an International Standard...Ch. 2.3 - How many different Zip Codes are possible using a...Ch. 2.3 - Telephone area codes are three-digit numbers of...Ch. 2.3 - Major credit cards such as VISA and MasterCard...Ch. 2.3 - The serial number on a dollar bill consists of a...Ch. 2.3 - The serial number on a new twenty-dollar bill...Ch. 2.3 - Each student at State University has a student ID...Ch. 2.3 - Each student at State College has a student ID...Ch. 2.3 - In Exercises 2338, find the indicated value. 4!Ch. 2.3 - In Exercises 2338, find the indicated value. 5!Ch. 2.3 - In Exercises 2338, find the indicated value. 10!Ch. 2.3 - In Exercises 2338, find the indicated value. 8!Ch. 2.3 - In Exercises 2338, find the indicated value. 20!Ch. 2.3 - In Exercises 2338, find the indicated value. 25!Ch. 2.3 - In Exercises 2338, find the indicated value. 6!4!Ch. 2.3 - In Exercises 2338, find the indicated value. 8!6!Ch. 2.3 - In Exercises 2338, find the indicated value. a....Ch. 2.3 - In Exercises 2338, find the indicated value. a....Ch. 2.3 - In Exercises 2338, find the indicated value....Ch. 2.3 - In Exercises 2338, find the indicated value....Ch. 2.3 - In Exercises 2338, find the indicated value....Ch. 2.3 - In Exercises 2338, find the indicated value....Ch. 2.3 - In Exercises 2338, find the indicated value....Ch. 2.3 - In Exercises 2338, find the indicated value....Ch. 2.3 - Find the value of n!(nr)!, when n=16 and r=14.Ch. 2.3 - Find the value of n!(nr)!, when n=19 and r=16.Ch. 2.3 - Find the value of n!(nr)!, when n=5 and r=5.Ch. 2.3 - Find the value of n!(nr)!, when n=r.Ch. 2.3 - Find the value of n!(nr)!r!, when n=7 and r=3.Ch. 2.3 - Find the value of n!(nr)!r!, when n=7 and r=4.Ch. 2.3 - Find the value of n!(nr)!r!, when n=5 and r=5.Ch. 2.3 - Find the value of n!(nr)!r!, when n=r.Ch. 2.3 - Answer the following questions using complete...Ch. 2.3 - Answer the following questions using complete...Ch. 2.3 - Answer the following questions using complete...Ch. 2.3 - The following questions are modeled after those...Ch. 2.3 - Prob. 51ECh. 2.3 - The following questions are modeled after those...Ch. 2.3 - Prob. 53ECh. 2.3 - Prob. 54ECh. 2.4 - In Exercises 112, find the indicated value: a. 7P3...Ch. 2.4 - In Exercises 112, find the indicated value: a. 8P4...Ch. 2.4 - In Exercises 112, find the indicated value: a. 5P5...Ch. 2.4 - In Exercises 112, find the indicated value: a. 9P0...Ch. 2.4 - In Exercises 112, find the indicated value: a....Ch. 2.4 - In Exercises 112, find the indicated value: a....Ch. 2.4 - In Exercises 112, find the indicated value: a....Ch. 2.4 - In Exercises 112, find the indicated value: a....Ch. 2.4 - In Exercises 112, find the indicated value: a....Ch. 2.4 - In Exercises 112, find the indicated value: a. xP1...Ch. 2.4 - In Exercises 112, find the indicated value: a. xP2...Ch. 2.4 - In Exercises 112, find the indicated value: a....Ch. 2.4 - a. Find 3P2. b. List all of the permutations of...Ch. 2.4 - a. Find 3C2. b. List all of the combinations of...Ch. 2.4 - Prob. 15ECh. 2.4 - a. Find 4P2. b. List all of the permutations of...Ch. 2.4 - Prob. 17ECh. 2.4 - An English class consists of twenty-three students...Ch. 2.4 - In how many ways can the letters in the word...Ch. 2.4 - A committee of four is to be selected from a group...Ch. 2.4 - A softball league has thirteen teams. If every...Ch. 2.4 - In a group of eighteen people, each person shakes...Ch. 2.4 - A softball league has thirteen teams. How many...Ch. 2.4 - Three hundred people buy raffle tickets. Three...Ch. 2.4 - A group of nine women and six men must select a...Ch. 2.4 - A group of ten seniors, eight juniors, six...Ch. 2.4 - Exercise2732, refer to a deck of fifty-two playing...Ch. 2.4 - Exercise2732, refer to a deck of fifty-two playing...Ch. 2.4 - Exercise2732, refer to a deck of fifty-two playing...Ch. 2.4 - Exercise2732, refer to a deck of fifty-two playing...Ch. 2.4 - How many five-card poker hands containing two pair...Ch. 2.4 - Exercise2732, refer to a deck of fifty-two playing...Ch. 2.4 - Exercises 3344 refer to lotteries; the order in...Ch. 2.4 - Exercises 3344 refer to lotteries; the order in...Ch. 2.4 - A 5/36 lottery requires choosing five of the...Ch. 2.4 - Exercises 3344 refer to lotteries; the order in...Ch. 2.4 - Exercises 3344 refer to lotteries; the order in...Ch. 2.4 - Exercises 3344 refer to lotteries; the order in...Ch. 2.4 - Over forty states participate in Powerball, a...Ch. 2.4 - Over forty states participate in Mega Millions, a...Ch. 2.4 - Exercises 33-44 refer to lotteries; the order in...Ch. 2.4 - Exercises 33-44 refer to lotteries; the order in...Ch. 2.4 - Exercises 33-44 refer to lotteries; the order in...Ch. 2.4 - Exercises 33-44 refer to lotteries; the order in...Ch. 2.4 - a. Find the sum of the entries in the first row of...Ch. 2.4 - a. Add adjacent entries of the sixth row of...Ch. 2.4 - Use Pascals Triangle to answer the following. a....Ch. 2.4 - Given the set S={a, b, c, d}, answer the...Ch. 2.4 - In Exercise 49-56, find the number of permutation...Ch. 2.4 - In Exercise 49-56, find the number of permutation...Ch. 2.4 - In Exercise 49-56, find the number of permutation...Ch. 2.4 - In Exercise 49-56, find the number of permutation...Ch. 2.4 - In Exercise 49-56, find the number of permutation...Ch. 2.4 - In Exercises 49-56, find the number of permutation...Ch. 2.4 - In Exercises 49-56, find the number of permutation...Ch. 2.4 - In Exercise 49-56, find the number of permutations...Ch. 2.4 - The words in each of Exercises 57-60 are homonyms...Ch. 2.4 - The words in each of Exercises 57-60 are homonyms...Ch. 2.4 - The words in each of Exercises 57-60 are homonyms...Ch. 2.4 - The words in each of Exercises 57-60 are homonyms...Ch. 2.4 - Prob. 61ECh. 2.4 - Prob. 62ECh. 2.4 - Exercise 6367 refer to the following: A baseball...Ch. 2.4 - Prob. 64ECh. 2.4 - Prob. 65ECh. 2.4 - Prob. 66ECh. 2.4 - Prob. 67ECh. 2.4 - Prob. 68ECh. 2.5 - Prob. 1ECh. 2.5 - In Exercises 1-10, find the cardinal numbers of...Ch. 2.5 - Prob. 3ECh. 2.5 - Prob. 4ECh. 2.5 - Prob. 5ECh. 2.5 - Prob. 6ECh. 2.5 - Prob. 7ECh. 2.5 - Prob. 8ECh. 2.5 - Prob. 9ECh. 2.5 - Prob. 10ECh. 2.5 - Prob. 11ECh. 2.5 - Prob. 12ECh. 2.5 - Prob. 13ECh. 2.5 - Prob. 14ECh. 2.5 - Prob. 15ECh. 2.5 - Consider the following one-to-one correspondence...Ch. 2.5 - Prob. 17ECh. 2.5 - Prob. 18ECh. 2.5 - Prob. 19ECh. 2.5 - Prob. 20ECh. 2.5 - Prob. 21ECh. 2.5 - Prob. 22ECh. 2.5 - Prob. 23ECh. 2.5 - Prob. 24ECh. 2.5 - Prob. 25ECh. 2.5 - Prob. 26ECh. 2.5 - Prob. 27ECh. 2.5 - Prob. 28ECh. 2.CR - Prob. 1CRCh. 2.CR - Prob. 2CRCh. 2.CR - Prob. 3CRCh. 2.CR - Prob. 4CRCh. 2.CR - Prob. 5CRCh. 2.CR - Prob. 6CRCh. 2.CR - Prob. 7CRCh. 2.CR - Prob. 8CRCh. 2.CR - Prob. 9CRCh. 2.CR - A survey of 1,000 college seniors yielded the...Ch. 2.CR - A survey of recent college graduates yielded the...Ch. 2.CR - A local anime fan club surveyed 67 of its members...Ch. 2.CR - An exit poll yielded following information...Ch. 2.CR - Prob. 14CRCh. 2.CR - Prob. 15CRCh. 2.CR - Prob. 16CRCh. 2.CR - Prob. 17CRCh. 2.CR - A certain model of pickup truck is available in...Ch. 2.CR - Each student at State University has a student ID...Ch. 2.CR - Prob. 20CRCh. 2.CR - Prob. 21CRCh. 2.CR - Prob. 22CRCh. 2.CR - A group of ten women and twelve men must select a...Ch. 2.CR - Prob. 24CRCh. 2.CR - Prob. 25CRCh. 2.CR - Using a standard deck of fifty-two cards no...Ch. 2.CR - Prob. 27CRCh. 2.CR - A 6/42 lottery requires choosing six of the...Ch. 2.CR - Prob. 29CRCh. 2.CR - Prob. 30CRCh. 2.CR - Prob. 31CRCh. 2.CR - Prob. 32CRCh. 2.CR - Prob. 33CRCh. 2.CR - Prob. 34CRCh. 2.CR - Prob. 35CRCh. 2.CR - Prob. 36CRCh. 2.CR - Prob. 37CRCh. 2.CR - Consider the following one to one correspondence...Ch. 2.CR - Prob. 39CRCh. 2.CR - Prob. 40CRCh. 2.CR - Prob. 41CRCh. 2.CR - Prob. 42CRCh. 2.CR - Prob. 43CRCh. 2.CR - Prob. 44CRCh. 2.CR - Prob. 45CRCh. 2.CR - Prob. 46CRCh. 2.CR - Prob. 47CRCh. 2.CR - Prob. 48CR
Knowledge Booster
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, subject and related others by exploring similar questions and additional content below.Similar questions
- For each of the following power series, find the interval of convergence and the radius of convergence: n² 1.0 (x + 1)" n=1 շո 3n 2. Σ n=1 (x-3)n n3arrow_forwardUse a known series to find a power series in x that has the given function as its sum: 1. xcos(x³) 2. In (1+x) xarrow_forwardif n is odd integer then 4 does not divide narrow_forward
- or W Annuities L Question 2, 5.3.7 > Find the future value for the ordinary annuity with the given payment and interest rate. PMT = $2,000; 1.65% compounded quarterly for 11 years. The future value of the ordinary annuity is $ (Do not round until the final answer. Then round to the nearest cent as needed.) example Get more help Q Search 30 Larrow_forwardFind the cdf of a random variable Y whose pdf is given by; 2, 0≤x≤1 1/3, 0≤x≤1 a) f(x)=3, 2≤x≤4 0, elsewhere 2, 1≤x≤2 b) f(x)= (3-x)2, 2≤x≤3 0, elsewherearrow_forwardFor all integers a and b, a + b is not ≡ 0(mod n) if and only if a is not ≡ 0(mod n)a or is not b ≡ 0(mod n). Is conjecture true or false?why?arrow_forward
- or W Annuities L Question 2, 5.3.7 > Find the future value for the ordinary annuity with the given payment and interest rate. PMT = $2,000; 1.65% compounded quarterly for 11 years. The future value of the ordinary annuity is $ (Do not round until the final answer. Then round to the nearest cent as needed.) example Get more help Q Search 30 Larrow_forwardThere are m users who share a computer system. Each user alternates between "thinking" intervals whose durations are independent exponentially distributed with parameter Y, and an "active" mode that starts by submitting a service re- quest. The server can only serve one request at a time, and will serve a request completely before serving other requests. The service times of different requests are independent exponentially distributed random variables with parameter μ, and also independent of the thinking times of the users. Construct a Markov chain model and derive the steady-state distribution of the number of pending requests, including the one presently served, if any.arrow_forwardUse laplace to transform.arrow_forward
- In order to find probability, you can use this formula in Microsoft Excel: The best way to understand and solve these problems is by first drawing a bell curve and marking key points such as x, the mean, and the areas of interest. Once marked on the bell curve, figure out what calculations are needed to find the area of interest. =NORM.DIST(x, Mean, Standard Dev., TRUE). When the question mentions “greater than” you may have to subtract your answer from 1. When the question mentions “between (two values)”, you need to do separate calculation for both values and then subtract their results to get the answer. 1. Compute the probability of a value between 44.0 and 55.0. (The question requires finding probability value between 44 and 55. Solve it in 3 steps. In the first step, use the above formula and x = 44, calculate probability value. In the second step repeat the first step with the only difference that x=55. In the third step, subtract the answer of the first part from the…arrow_forwardIf a uniform distribution is defined over the interval from 6 to 10, then answer the followings: What is the mean of this uniform distribution? Show that the probability of any value between 6 and 10 is equal to 1.0 Find the probability of a value more than 7. Find the probability of a value between 7 and 9. The closing price of Schnur Sporting Goods Inc. common stock is uniformly distributed between $20 and $30 per share. What is the probability that the stock price will be: More than $27? Less than or equal to $24? The April rainfall in Flagstaff, Arizona, follows a uniform distribution between 0.5 and 3.00 inches. What is the mean amount of rainfall for the month? What is the probability of less than an inch of rain for the month? What is the probability of exactly 1.00 inch of rain? What is the probability of more than 1.50 inches of rain for the month? The best way to solve this problem is begin by creating a chart. Clearly mark the range, identifying the lower and upper…arrow_forwardProblem 1: The mean hourly pay of an American Airlines flight attendant is normally distributed with a mean of 40 per hour and a standard deviation of 3.00 per hour. What is the probability that the hourly pay of a randomly selected flight attendant is: Between the mean and $45 per hour? More than $45 per hour? Less than $32 per hour? Problem 2: The mean of a normal probability distribution is 400 pounds. The standard deviation is 10 pounds. What is the area between 415 pounds and the mean of 400 pounds? What is the area between the mean and 395 pounds? What is the probability of randomly selecting a value less than 395 pounds? Problem 3: In New York State, the mean salary for high school teachers in 2022 was 81,410 with a standard deviation of 9,500. Only Alaska’s mean salary was higher. Assume New York’s state salaries follow a normal distribution. What percent of New York State high school teachers earn between 70,000 and 75,000? What percent of New York State high school…arrow_forward
arrow_back_ios
SEE MORE QUESTIONS
arrow_forward_ios
Recommended textbooks for you
- College Algebra (MindTap Course List)AlgebraISBN:9781305652231Author:R. David Gustafson, Jeff HughesPublisher:Cengage LearningAlgebra: Structure And Method, Book 1AlgebraISBN:9780395977224Author:Richard G. Brown, Mary P. Dolciani, Robert H. Sorgenfrey, William L. ColePublisher:McDougal LittellHolt Mcdougal Larson Pre-algebra: Student Edition...AlgebraISBN:9780547587776Author:HOLT MCDOUGALPublisher:HOLT MCDOUGAL
- College AlgebraAlgebraISBN:9781305115545Author:James Stewart, Lothar Redlin, Saleem WatsonPublisher:Cengage Learning

College Algebra (MindTap Course List)
Algebra
ISBN:9781305652231
Author:R. David Gustafson, Jeff Hughes
Publisher:Cengage Learning

Algebra: Structure And Method, Book 1
Algebra
ISBN:9780395977224
Author:Richard G. Brown, Mary P. Dolciani, Robert H. Sorgenfrey, William L. Cole
Publisher:McDougal Littell

Holt Mcdougal Larson Pre-algebra: Student Edition...
Algebra
ISBN:9780547587776
Author:HOLT MCDOUGAL
Publisher:HOLT MCDOUGAL



College Algebra
Algebra
ISBN:9781305115545
Author:James Stewart, Lothar Redlin, Saleem Watson
Publisher:Cengage Learning
Find number of persons in a part with 66 handshakes Combinations; Author: Anil Kumar;https://www.youtube.com/watch?v=33TgLi-wp3E;License: Standard YouTube License, CC-BY
Discrete Math 6.3.1 Permutations and Combinations; Author: Kimberly Brehm;https://www.youtube.com/watch?v=J1m9sB5XZQc;License: Standard YouTube License, CC-BY
How to use permutations and combinations; Author: Mario's Math Tutoring;https://www.youtube.com/watch?v=NEGxh_D7yKU;License: Standard YouTube License, CC-BY
Permutations and Combinations | Counting | Don't Memorise; Author: Don't Memorise;https://www.youtube.com/watch?v=0NAASclUm4k;License: Standard Youtube License
Permutations and Combinations Tutorial; Author: The Organic Chemistry Tutor;https://www.youtube.com/watch?v=XJnIdRXUi7A;License: Standard YouTube License, CC-BY