Probability and Statistics for 12-Year-Olds (and Maybe You)
Plain English Simply Explained,
Lessons and Ideas for Students,
Gamblers, and Decision Makers
By
DAVID SKLANSKY
Technical Consultant
MASON MALMUTH
A product of
Two Plus Two Publishing LLC
FIRST EDITION
Oct 2020
Probability and Statistics for 12-Year-Olds (and Maybe You)
COPYRIGHT 2020 David Sklansky and Two Plus Two Publishing LLC
All rights reserved. Printed in the United States of America.
No part of this book may be reproduced or transmitted in any form, by any means, electronic or mechanical, including photocopying and recording, or by any information storage or retrieval system without the express permission in writing from the publisher.
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ISBN10: 1-880685-63-9
ISBN13: 978-1-880685-63-1
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Table of Contents
About David Sklansky
David Sklansky is the author of 16 books about poker, gambling, and strategy. His best known book, The Theory of Poker, which was first written (as Sklansky on Poker Theory ) over 40 years ago, is still considered the most important book on the subject.
David has won three World Series of Poker bracelets along with dozens of other poker tournaments as well as other types of gambling tournaments. He has consulted with several casino companies and is the holder of five patents. In addition, he invented the game that was to become Caribbean Stud and testified in front of Clintons Presidential Gambling Commission.
Hes still generally considered the number one authority on gambling theory and attributes his standing in the gambling community to the following three facts:
The fact that he presents his ideas as simply as possible (sometimes with another author) even though these ideas frequently involve concepts that are deep, subtle, and not to be found elsewhere.
The fact that Davids teachings have proven to be accurate.
The fact that to this day a large portion of his income is still derived from gambling (usually poker, but occasionally blackjack, sports betting, horses, video games, casino promotions, or casino tournaments).
Note: David Sklansky is available for lectures and seminars. For more information, contact .
About Mason Malmuth
Mason Malmuth was born and raised in Coral Gables, Florida. In 1973 he received his BS in Mathematics from Virginia Tech, and completed their Masters program in 1975, also in Mathematics. While working for the United States Census Bureau in 1980, Mason stopped overnight in Las Vegas while driving to his new assignment in California. He was immediately fascinated by the games, and gambling became his major interest.
After arriving in California, he discovered that poker was legal and began playing in some of the public cardrooms as well as taking periodic trips to Las Vegas where he would play both poker and blackjack. In 1982, he went to work for the Northrop Corporation (now Northrop-Grumman) as a mathematician and moved to Los Angeles where he could conveniently pursue his interest in poker in the large public cardrooms in Gardena, Bell Gardens, and Commerce.
In 1983, his first article Card Domination The Ultimate Blackjack Weapon was published in Gambling Times Magazine. In 1987, he left his job with the Northrop Corporation to begin a career as both a full-time gambler and a gambling writer. He has had over 600 articles published in various magazines and is the author or co-author of 18 books. These include Gambling Theory and Other Topics where he tries to demonstrate why only a small number of people are highly successful at gambling. In this book he introduces the reader to the concept of Non-Self-Weighting Strategies and explains why successful gambling is actually a balance of luck and skill. Other books he has co-authored include Hold 'em Poker For Advanced Players with David Sklansky, Seven-Card Stud For Advanced Players with David Sklansky and Ray Zee, and Small Stakes Hold 'em: Winning Big with Expert Play with Ed Miller and David Sklansky. All of these are considered the definitive works on these games.
His company, Two Plus Two Publishing LLC, has sold over two and a half million books and currently has 46 titles to its credit. These books are recognized as the best in their field and are thoroughly studied by those individuals who take gambling seriously.
In addition, Mason also heads up Two Plus Two Interactive LLC which produces www.twoplustwo.com where the largest English-speaking poker community on the Internet is located. At the time of this writing, it contains approximately 100 forums where thousands of posts appear each day.
Introduction
I wasnt just trying to be cute when titling this book Probability and Statistics for 12-Year-Olds (and Maybe You). That title was chosen because I know that those students who hate, or are weak at math, have probably learned that the self-help math books that purport to be easy, actually arent. But this book is different. It really is written simply enough, with the help of various tricks of my trade, so that even a moderately smart twelve year old (or his parents) can understand it.
Of course, I dont expect most of my readers to be precocious youngsters. The title is used mainly to reduce anxiety among the math phobic who normally avoid learning more math than they are forced to. But there are at least two categories of people who have to know some basic probability and statistics whether they like it or not. One category is college students who are majoring in a field that requires them to take an introductory probability course. The other category is serious, possibly professional, gamblers and game players. Both of these types usually include many people who would struggle with math books as they are currently written. But not this one. Unlike other authors, Im not concerned with rigor, or norms or jargon. The words I use will be presented in a conversational style most of the time, similar to the way I (very successfully) tutor students. But when done with the book, youll be able to answer most gambling problems and/or be well on your way to understanding what your professor is talking about.
And changing the subject, I want to thank Andres Ochoa of Creel Printing for the cover art. I also need to thank Lex Martin for his comments and Mat Sklansky for helping with the proof reading. And finally, I want to thank Mason Malmuth of Two Plus Two Publishing LLC for consultation, help with the editing, and all other work involved with publishing this book.
Chapter One
Chances of Winning Both Bets
Most probability books start out with an explanation of how probability is measured (i.e. a number between zero and one) and philosophical explanations of what is meant when we specify that an event has a certain probability. Things that most of you already know or dont really need to know if your main goals are a good grade or making profitable bets.
Ill get to that esoteric stuff later. But before that happens, lets jump right into solving one of the most common types of probability problems. Namely figuring the chances of winning all of your bets when you know the chances of winning each individual bet.
The answer is often quite straightforward. You multiply those chances.
Since chances are usually expressed as a fraction, you would simply be multiplying those fractions. (For those who forgot their grade school arithmetic, that means multiply the numerators to get a new numerator (top) and put that over the number you get when you multiply the denominators (bottoms). Fractions that are used to measure probability can be put in lower terms in the normal way but it is not necessary and sometimes not even desirable to do that.