Editing 2379: Probability Comparisons

{{comic
| number    = 2379
| date      = October 30, 2020
| title     = Probability Comparisons
| image     = probability comparisons new.png
| titletext = Call me, MAYBE.
}}

==Explanation==
This is a list of probabilities for different events. There are numerous recurring themes, of which the most common are free throws (13 entries), birthdays (12), dice (12, split about evenly between 6-sided (d6) and 20-sided (d20) types), {{w|M&M's|M&M}} candies (11), playing cards (9), {{w|NBA}} basketball mid-game victory predictions (9), {{w|Scrabble}} tiles (7), coins (7), white Christmases (7) and the NBA players {{w|Stephen Curry}} plus {{w|LeBron James}} (7 each). Themes are variously repeated and combined, for humorous effect. For instance, there are entries for both the probability that St. Louis will have a white Christmas (21%) and that it will not (79%). Also given is the 40% probability that a random Scrabble tile will contain a letter from the name "Steph Curry". There are 80 items in the list, the last two of which devolve into absurdity - perhaps from the stress of preparing the other 78 entries.

The list may be an attempt to better understand probabilistic election forecasts for the {{w|2020 United States presidential election}}, which was four days away at the time this comic was published and had also been alluded to in [[2370: Prediction]] and [[2371: Election Screen Time]]. Statistician and {{w|psephologist}} [[Nate Silver]] is referenced in one of the list items. On the date this cartoon was published, Nate Silver's website {{w|FiveThirtyEight}} was [https://projects.fivethirtyeight.com/2020-election-forecast/ publishing forecast probabilities] of [[Donald Trump]] and [[Joe Biden]] winning the US Presidential election. On 31 October 2020, the forecast described the chances of Donald Trump winning as "roughly the same as the chance that it’s raining in downtown Los Angeles. It does rain there. (Downtown L.A. has about 36 rainy days per year, or about a 1-in-10 shot of a rainy day.)" A day previously, when the chances were 12%, the website had also described Trump's chances of winning as "slightly less than a six sided die rolling a 1". The probabilities are calculated from [https://xkcd.com/2379/sources/ these sources], as mentioned in the bottom left corner of the comic.

The title text refers to the song "{{w|Call Me Maybe}}" by {{w|Carly Rae Jepsen}} (cited twice in the list). "MAYBE" is emphasized, perhaps because the probability of getting her phone number correct, as in the last item in the list, is very low. The capitalization could also be a reference to Scrabble tiles, as was previously mentioned in association with Carly Rae Jepsen.

==Table==
{| class="wikitable sortable"
! Odds
! Text
! Explanation
|-
| 0.01%
| You guess the last four digits of someone's {{w|Social Security Number}} on the first try
| There are nine digits in a {{w|Social Security Number}}, but the last four are commonly used as an identity verification factor. (1/10)<sup>4</sup> = 0.0001, or 0.01%
|-
| 0.1%
| Three randomly chosen people are all left-handed
| The chances of having left-{{w|handedness}} is about [https://www.healthline.com/health/left-handers-and-health-risk 10%], and 10%<sup>3</sup> = 0.1%.
|-
| rowspan="2" | 0.2%
| You draw 2 random {{w|Scrabble}} tiles and get M and M
| This appears to be an error. Under standard English {{w|Scrabble letter distribution}} there are 100 tiles of which 2 are M. This would give a probability of randomly drawing M and M as 2/100 × 1/99 ≈ 0.02%. However, other language editions of Scrabble have different letter distributions, some of which could allow this to be true.
|-
| You draw 3 random {{w|M&Ms}} and they're all red
| Depending on the source of one's M&Ms in the U.S., the proportion of reds is either 0.131 or 0.125 .  0.131^3 ≈ 0.225%; 0.125^3 ≈ 0.177% .
|-
| 0.3%
| You guess someone's birthday in one try.
| 1/365 ≈ 0.27%. Taking into account that a person might have been born February 29, the probability with a random guess is slightly lower.  If the guesser knows on which days there are slightly more births (for example, early October, believed to be because of conceptions occurring on the evening of December 31) and which days there are slightly fewer (for examples, holidays on which a planned, pre-scheduled C-section is unlikely to be held), then the probability is slightly higher.
|-
| rowspan="2" | 0.5%
| An {{w|NBA}} team down by 30 at halftime wins
| This calculation, along with all related ones, uses the source [http://stats.inpredictable.com/nba/wpCalc.php NBA Win Probability Calculator]. Entering Q2, 0:00 and -30 into the calculator yields 0.6% .
|-
| You get 4 M&Ms and they're all brown or yellow
| Depending on the source of one's M&Ms in the U.S., the proportion of them that is brown or yellow is either 0.25 or 0.259 .  0.25<sup>4</sup>≈ 0.39%; 0.259<sup>4</sup> ≈ 0.45% . Both are closer to 0.4% .
|-
| rowspan="2" | 1%
| {{w|Steph Curry}} gets two free throws and misses both
| Curry is a 91% career free throw shooter, so the percentage of missing 1 free throw is about 9%. The chance of missing 2 free throws is about 0.8% ≈ 1%.
|-
| {{w|LeBron James}} guesses your birthday, if each guess costs one free throw and he loses if he misses
| LeBron James' free-throw odds are ~73% . The odds of him winning on the first round are 1/365, for the second (364/365)(1/364)(0.73), for the third (363/365)(1/363)(0.73)<sup>2</sup>... Summing all of these from 1 to 365 gives us his total odds of winning at any point in the game are ≈ 1.015% .
|-
| rowspan="2" | 1.5%
| You get two M&Ms and they're both red
| Depending on the source of one's M&Ms in the U.S., the proportion of reds is either 0.131 or 0.125 . 0.131^2 ≈ 1.7%; 0.125^2 ≈ 1.6% . 
|-
| You share a birthday with a {{w|Backstreet Boys|Backstreet Boy}}
|Each of the five Backstreet Boys has a different birthday, so the odds that you share a birthday with one is 5/365 ≈ 1.3% .
|-
| 2%
| You guess someone's card on the first try
| There are 52 cards in a normal deck of cards (excluding jokers), so the probability is 1/52, which is approximately 1.9%.
|-
| rowspan="2"| 3%
| You guess 5 coin tosses and get them all right
| The chance of correctly predicting a coin toss is 0.5, or 50%. The chance of predicting 5 in a row is 0.5<sup>5</sup>, or 3.125%.
|-
| Steph Curry wins that birthday free throw game
| Swap out 0.73 for 0.91 in the above calculations to find Steph Curry's odds of winning. This sum yields ~3.04% .
|-
| rowspan="3"| 4%
| You sweep a 3-game {{w|rock paper scissors}} series
| Picking randomly, you have a 1 in 3 chance of beating an opponent on the first try. (1/3)<sup>3</sup> = 1/27 ≈ 4% .
|-
| {{w|Portland, Oregon}} has a {{w|White Christmas (weather)|white Christmas}}
| According to Randall's source (from the ''Bulletin of the American Meteorological Society''), the probability of snow cover in Portland is 4%.
|-
| You share a birthday with two {{w|US Senator}}s
| At the time this comic was published, 15 days were birthdays for more than one Senator, and 15/365 ≈ 4%.<ref>Rand Paul and John Thune - January 7<br/>
Chris Van Hollen and Roy Blunt - January 10<br/>
Tina Smith and James Lankford - March 4<br/>
Tammy Duckworth and Mitt Romney - March 12<br/>
Angus King and Patrick Leahy - March 31<br/>
Jim Risch and Ron Wyden - May 3<br/>
Dianne Feinstein and Elizabeth Warren - June 22<br/>
Todd Young and Joe Manchin - August 24<br/>
Kamala Harris, Brian Schatz and Sheldon Whitehouse - October 20<br/>
Jeff Merkley and Mike Rounds - October 24<br/>
Jim Inhofe and Pat Toomey - November 17<br/>
Dick Durbin and John Kennedy - November 21<br/>
Rick Scott and Gary Peters - December 1<br/>
John Boozman and David Perdue - December 10<br/>

Based on [https://en.wikipedia.org/wiki/List_of_current_United_States_senators List of current US Senators on Wikipedia] (and processed through [https://bit.ly/2HZeqQs this Google sheet)].
</ref>
|-
| rowspan="2"| 5%
| An NBA team down 20 at halftime wins
| Entering Q2, 0:00 and -20 into the NBA Win Probability Calculator yields 5.2% or 5.3% .
|-
| You roll a natural 20
| A natural 20 indicates a critical hit in the {{w|Dungeons & Dragons}} role playing game. "Natural" means that it is the number showing when rolling a d20 (a 20-sided die), as opposed to an overall total of 20 when counting the die roll plus modifiers. There are twenty sides to a d20 die, so 1/20 = 0.05 = 5% .
|-
| 6%
| You correctly guess someone's card given 3 tries
| Picking a random card within 3 times gives 1 - (51/52)(50/51)(49/50) ≈ 6% .
|-
| 7%
| LeBron James gets two free throws and misses both
| James' career free throw percentage is 73%, so the probability of a miss is 0.27, or 27%. The probability of 2 misses is (0.27)<sup>2</sup>, which is about 7%.
|-
| 8%
| You correctly guess someone's card given 4 tries
| Assuming you guess four different cards, 4/52 = 0.0769 ≈ 8% . Assuming that you guess the same card, 1 - (51/52)(50/51)(49/50)(48/49) ≈ 7.7%.
|-
| 9%
| Steph Curry misses a free throw
| Curry's career free throw percentage is 91%, so the probability of a miss is 9%.
|-
| rowspan="2"|10%
| You draw 5 cards and get the Ace of Spades
| There are 52 cards in a normal deck of cards (excluding jokers), and the Ace of Spades is one of them.{{Citation needed}} The chances of getting the card is 1 - 51/52 * 50/51 * 49/50 * 48/49 * 47/48 which is approximately 0.096, which rounds to the given 0.1 or 10%.
|-
| There's a {{w|Moment magnitude scale|magnitude}} 8+ earthquake in the next month
| Note that, unlike other earthquake examples, this does not specify where the earthquake occurs. From 1905 to 2021, there have been 98 earthquakes magnitude 8+ recorded around the world.
|-
| 11%
| You sweep a 2-game rock paper scissors series
| You have a 1/3 chance of winning the first comparison and a 1/3 chance of winning the second. (1/3) * (1/3) = 1/9 ~ 0.11 = 11% .
|-
| rowspan="3"|12%
| A randomly-chosen American lives in {{w|California}}
| California is the most populous state in the US. Out of the approximately 328.2 million Americans (as of 2019), 39.51 million live in California. This means that a randomly chosen American has about a 39.51/328.2 ≈ 10.33% chance of living in California. Due to population change and rounding based on different sources, this could be pushed to 12%.
|-
| You correctly guess someone's card given 6 tries
| Assuming you don't repeat previous wrong guesses, the probability is 6/52 ≈ 11.54%.
|-
| You share a birthday with a {{w|US President}}
| Presidents {{w|James Polk}} and {{w|Warren Harding}} share a birthday, and are the only presidents so far (in 2020) to do so. Additionally, {{w|Grover Cleveland}} served two non-consecutive terms and is counted twice (as the 22nd and 24th presidents). He therefore shares a birthday with himself. With 43 distinct birthdays, the odds of sharing a birthday are 43/365 ≈ 12%. (This does not consider February 29 or that more births occur on some days than others.)
|-
| rowspan="3"|13%
| A {{w|Dice#Polyhedral_dice|d6}} beats a {{w|Dice#Polyhedral_dice|d20}}
| The odds of a d6 beating a d20 are (0 + 1 + 2 + 3 + 4 + 5)/(6*20) = 0.125 ≈ 13% .
|-
| An NBA team down 10 going into the 4th quarter wins
| Entering Q3, 0:00 and -10 into the NBA Win Probability Calculator yields 12.6% or 12.8% .
|-
| You pull one M&M from a bag and it's red
| Depending on the source of one's M&Ms in the U.S., the proportion of reds is either 0.131 or 0.125 .
|-
| 14%
| A randomly drawn scrabble tile beats a D6 die roll
| {{w|Scrabble}} is a game in which you place lettered tiles to form words. Most of the scores per letter are 1, making it rare to beat a d6. The odds are (70/100)(0) + (7/100)(1/6) + (8/100)(2/6) + (10/100)(3/6) + (1/100)(4/6) + (4/100)(6/6) ≈ 14%.
|-
| 15%
| You roll a D20 and get at least 18
| The set of "at least 18" on a d20 is 18, 19 and 20. The odds of rolling one of these is 3/20 = 15% .
|-
| 16%
| Steph Curry gets two free throws but makes only one
| Steph Curry's free throw percentage is 91%, so (0.91)(0.09) = 8.19% . However, the order of these is irrelevant, so the total odds are 16.38% .
|-
| 17%
| You roll a D6 die and get a 6
| The odds are 1/6 ≈ 17% .
|-
| 18%
| A D6 beats or ties a D20
| The odds are (1 + 2 + 3 + 4 + 5 + 6)/(120) = 17.5% .
|-
| 19%
| At least one person in a random pair is left-handed
| The chances of being left handed is about 10%, so the probability of both people in the pair not being left-handed is 0.9<sup>2</sup>=0.81, and 1-0.81=0.19.
|-
| 20%
| You get a dozen M&Ms and none of them are brown
| Depending on the source of one's M&Ms in the U.S., the proportion of browns is either 0.124 or 0.125 .  (1 - 0.125)^12 ≈ 20.1%; (1 - 0.124)^12 ≈ 20.4% .
|-
| 21%
| {{w|St. Louis}} has a white Christmas
| According to Randall's source, the probability of snow cover in St. Louis is 21%.
|-
| 22%
| An NBA team wins when they're down 10 at halftime
| Entering Q2, 0:00 and -10 into the NBA Win Probability Calculator yields 22.3% or 22.5% .
|-
| rowspan="2"| 23%
| You get an M&M and it's blue
| Depending on the source of one's M&Ms in the U.S., the proportion of blues is either 0.207 or 0.25 . 
|-
| You share a birthday with a US senator
| There are 100 Senators, but 31 Senators share 15 birthdays and 69 Senators have unique birthdays, so there are a total of 84 days of the year that are the birthday of a Senator.
|-
| 24%
| You correctly guess that someone was born in the winter
| By date, the cited U.S. census data gives that 24,545,230 of the 101,909,161 people were born in the ''meteorological'' winter (December through February), or 24.09%.
|-
| rowspan="2"| 25%
| You correctly guess that someone was born in the fall
| By date, the cited U.S. census data gives that 25,701,366 of the 101,909,161 people were born in the ''meteorological'' fall (September through November), or 25.22%.
|-
| You roll two plain M&Ms and get M and M.
| An M&M can land on one of two sides, one with an M and one without. The odds of "rolling" two Ms is 1/4 = 25%. The term "rolling" is used jokingly in reference to the d6s and d20s above, suggesting that an M&M is a standard d2; this becomes especially true once you consider that a more accurate reference would have been to a coin, not a die.
|-
| 26%
| You correctly guess someone was born in the summer
| By date, the cited U.S. census data gives that 26,475,119 of the 101,909,161 people were born in the ''meteorological'' summer (June through August), or 25.98%.
|-
| 27%
| LeBron James misses a free throw
| James' career free throw percentage is 73%, so the probability of missing is 27%. 
|-
| 32%
| {{w|Pittsburgh}} has a white Christmas
| According to Randall's source, the probability of snow cover in Pittsburgh is 32%.
|-
| rowspan="3"| 33%
| A randomly chosen Star Wars movie (Episodes I-IX) has "of the" in the title
| The movies that have "of the" in their titles are Episodes II (Attack of the Clones), III (Revenge of the Sith) and VI (Return of the Jedi). This gives the odds of 3/9 ≈ 33%.
|-
| You win the Monty Hall sports car by picking a door and refusing to switch
| The {{w|Monty Hall problem}} is a counterintuitive logic problem, in which you pick one of three doors at random. One of the doors has a car behind it, so the odds that you picked the door are 1/3 ≈ 33%. Thus, by not switching doors, your odds remain the same. The Monty Hall problem has previously appeared in [[1282: Monty Hall]] and [[1492: Dress Color]].
|-
| You win rock paper scissors by picking randomly
| The odds of beating an opponent on the first try by picking randomly is 1/3 ≈ 33% .
|-
| 34%
| You draw five cards and get an ace
| The odds are 1 - (48/52)(47/51)(46/50)(45/49)(44/48) ≈ 34% .
|-
| 35%
| A random Scrabble tile is one of the letters in "random"
| The odds of drawing a letter in "random" are (6 + 9 + 6 + 4 + 8 + 2)/100 = 35% .
|-
| 39%
| LeBron James gets two free throws but misses one
| LeBron James' free throw percentage is 73% , so the odds are (0.73)(0.27) = 19.71% . However, the order is irrelevant, so the odds are actually twice, or 39.42% .
|-
| 40%
| A random Scrabble tile is a letter in "Steph Curry"
| The odds of drawing a letter in "Steph Curry" are (4 + 6 + 12 + 2 + 2 + 2 + 4 + 6 + 2)/100 = 40% .
|-
| 46%
| There's a magnitude 7 quake in LA within 30 years
|
|-
| rowspan="2"|48%
| {{w|Milwaukee}} has a white Christmas
| According to Randall's source, the probability of snow cover in Milwaukee is 48%.
|-
| A random Scrabble tile is a letter in Carly Rae Jepsen
| The odds of a Scrabble tile being in her name are (2 + 9 + 6 + 4 + 2 + 12 + 1 + 2 + 4 + 6)/100 = 48% .
|-
| 50%
| You get heads in a coin toss
| There are two options in a coin toss, heads or tails, so the odds of getting heads is 50% (1/2).  Uncharacteristically for Randall, this ignores the minuscule possibility that the coin might land on its edge.
|-
| 53%
| {{w|Salt Lake City}} has a white Christmas
| According to Randall's source, the probability of snow cover in Salt Lake City is 53%.
|-
| 54%
| LeBron James gets two free throws and makes both
| James' career free throw percentage is 73%, so the probability of making 2 free throws is (73%)<sup>2</sup> = 53.9%.
|-
| 58%
| A random Scrabble tile is a letter in "Nate Silver"
| {{w|Nate Silver}} is a recurring person on xkcd. The odds of a Scrabble tile being in his name are (6 + 9 + 6 + 12 + 4 + 9 + 4 + 2 + 6)/100 = 58% . <!-- explain where these numbers come from -->
|-
| 60%
| You get two M&Ms and neither is blue
| Depending on the source of one's M&Ms in the U.S., the proportion of blues is either 0.207 or 0.25 .  (1 - 0.207)^2 ≈ 62.9%; (1 - 0.25)^2 ≈ 56.3%.
|-
| 65%
| {{w|Burlington, Vermont}} has a white Christmas
| According to Randall's source, the probability of snow cover in Burlington is 65%.
|-
| 66%
| A randomly chosen movie from the main Lord of the Rings trilogy has “of the” in the title twice
| The titles are:
* ''The Lord '''of the''' Rings: The Fellowship '''of the''' Ring''
* ''The Lord '''of the''' Rings: The Two Towers''
* ''The Lord '''of the''' Rings: The Return '''of the''' King''
All of them have “of the” at least once, in “The Lord of the Rings”, but only the first and third have it twice, and 2/3 ≈ 66%. This number typically rounds up to 67% , however, and it is unclear why it is not, given that the same reduced fraction is written in the 67% category below.
|-
| 67%
| You roll at least a 3 with a d6
| The set of "at least 3" on a d6 refers to 3, 4, 5 and 6. The odds are 4/6 ≈ 67%.
|-
| 71%
| A random Scrabble tile beats a random dice roll
| This is a typo, as the correct probability is at the 14% entry. A random (d6) die roll beats a random Scrabble tile 71% of the time. [[Randall]] probably meant to write '''A random d6 dice roll''' beats '''a random Scrabble tile'''.
|-
| 73%
| LeBron James makes a free throw
| This is James' career free throw percentage, 73%.
|-
| 75%
| You drop two M&Ms and one of them ends with the "M" up so it's clear they're not Skittles
| The odds of at least one 'M' showing up is 1 - (1/4) = 75% . The reference to {{w|Skittles}} is that the two candies look similar to one another, and Randall has probably bit into a Skittle thinking it was an M&M, or vice versa. This trick might prevent that from happening in the future.
|-
| 76%
| You get two M&Ms and neither is red
| Depending on the source of one's M&Ms in the U.S., the proportion of reds is either 0.131 or 0.125 .  (1 - 0.131)^2 ≈ 75.5%; (1 - .125)^2 ≈ 76.6%.
|-
| 77%
| You get an an M&M and it's not blue
| Depending on the source of one's M&Ms in the U.S., the proportion of blues is either 0.207 or 0.25 .  (1 - 0.207) = 79.3%; (1 - 0.25) = 75.0%.
|-
| 78%
| An NBA team wins when they're up 10 at halftime
| Entering Q2, 0:00 and 10 into the NBA Win Probability Calculator yields 77.5% or 77.7% .
|-
| 79%
| St. Louis doesn't have a white Christmas
| According to Randall's source, the probability of snow cover in St. Louis is 21%, thus the probability of ''no'' snow cover is 79%.
|-
| 81%
| Two random people are both right-handed
| The probability of 1 person being right-handed is about 90%, thus the probability of 2 right-handers is (90%)<sup>2</sup> = 81%.
|-
| 83%
| Steph Curry gets two free throws and makes both
| Curry's career free throw percentage is 91%, so the probability of making 2 free throws is (91%)<sup>2</sup> = 82.81%.
|-
| 85%
| You roll a d20 and get at least a 4
| The set "at least 4" on a d20 refers to 4, 5, 6... 18, 19, 20. The odds of this are 17/20 = 85% .
|-
| rowspan="2"| 87%
| An NBA team up by 10 going into the 4<sup>th</sup> quarter wins
| Entering Q3, 0:00 and 10 into the NBA Win Probability Calculator yields 87.2% or 87.4% .
|-
| Someone fails to guess your card given 7 tries
|Assuming they guess seven different cards, there are 45 unguessed cards left. 45/52 = 0.865384615 ~ 86.5% 
|-
| 88%
| A randomly chosen American lives outside California
| This is the opposite of the previous California probability. As the probability of an American living in California is 12%, the opposite would be 88%.
|-
| 89%
| You roll a 3 or higher given two tries
| The probability of rolling a 3 or higher (on a 6-sided die) is 66%, so the percentage of rolling a 3 or higher given 2 tries is 1 - (1-.66)<sup>2</sup> = 89%.
|-
| 90%
| Someone fails to guess your card given 5 tries
| Assuming they guess five different cards, there are 47 unguessed cards left. 47/52 = 0.90385 ~ 90% 
|-
| rowspan="2"| 91%
| You incorrectly guess that someone was born in August
| If the odds of someone being born in August are ~9% , then the odds that a person was not born in August are ~91%. (In an average month, 8 1/3% of the population was born.  August has an above average number of days, but still only about 8.5% of the year is in August.)
|-
| Steph Curry makes a free throw
| This is Curry's career free throw percentage, 91%.
|-
| 92%
| You guess someone's birth month at random and are wrong
| On average, a month lasts 8⅓% of the year. Thus, if you were to guess someone's birth month at random, you would be wrong 91 ⅔% of the time.
|-
| 93%
| Lebron James makes a free throw given two tries
| James' career free throw percentage is 73%, so the percentage of his making at least 1 free throw given 2 tries is 1 - (1-.73)<sup>2</sup> = 93%.
|-
| 94%
| Someone fails to guess your card given 3 tries
| The odds of this happening are (51/52)(50/51)(49/50) ≈ 94% .
|-
| 95%
| An NBA team wins when they're up 20 at halftime
| Entering Q2, 0:00 and 20 into the NBA Win Probability Calculator yields 94.7% or 94.8% .
|-
| 96%
| Someone fails to guess your card given 2 tries
| The odds of this happening are (51/52)(50/51) ≈ 96% .
|-
| 97%
| You try to guess 5 coin tosses and fail
| The odds of this happening are 1 - (1/2)<sup>5</sup> ≈ 97% .
|-
| 98%
| You incorrectly guess someone's birthday is this week
| The odds of this happening are about 51/52 ≈ 98%. (This depends on the week; there are more births in early October and fewer in holiday weeks.)
|-
| 98.5%
| An NBA team up 15 points with 8 minutes left wins
| Entering Q4, 8:00 and 15 into the NBA Win Probability Calculator yields 98.0% or 98.6% .
|-
| 99%
| Steph Curry makes a free throw given two tries
| James' career FT percentage is 91%, so the percentage of his making at least 1 FT given 2 tries is 1 - (1-.91)<sup>2</sup> = 99%.
|-
| 99.5%
| An NBA team that's up by 30 points at halftime wins
| Entering Q2, 0:00 and 30 into the NBA Win Probability Calculator yields 99.4% .
|-
| 99.7%
| You guess someone's birthday at random and are wrong
| The odds of this are 364/365 ≈ 99.7%.
|-
| 99.8%
| There's not a {{w|Moment magnitude scale|magnitude}} 8 quake in {{w|California}} next year
|
|-
| 99.9%
| A random group of three people contains a right-hander
| About 90% of people are right-handed, so the percentage of at least 1 right-hander in a group of 3 is 1 - (1-.9)<sup>3</sup> = 99.9%.
|-
| 99.99%
| You incorrectly guess the last four digits of someone's social security number
| There are nine digits in a Social Security Number, but the last four are commonly used as an identity verification factor. The odds of this are 1 - (1/10)<sup>4</sup> = 99.99% .
|-
| 99.9999999999999995%
| You pick up a phone, dial a random 10-digit number, say "Hello Barack Obama, there's just been a {{w|Moment magnitude scale|magnitude}} 8 earthquake in {{w|California}}!" and are wrong
| This probability combines two events.

First, the probability that a random 10-digit telephone number belongs to Obama is 1/10<sup>10</sup>. This ignores potential complications from Obama owning multiple phones or failing to answer personally (perhaps using an assistant or answering machine). Additionally, it assumes numbers are dialed at random rather than making more intelligent guesses, such as using likely addresses to guess area codes.

Second, the probability of a magnitude 8 California quake is given in a previous entry as 0.2% per year. Although the time window for an earthquake to "just occur" is not given, a 15 minute window corresponds (within rounding error) to the total probability given.
|-
| 0.00000001%
| You add "Hang on, this is big — I'm going to loop in Carly Rae Jepsen", dial another random 10-digit number and she picks up
| Carly Rae Jepsen is a Canadian singer. As Canada uses the 10-digit {{w|North American Numbering Plan}}, the odds of a random number being hers would be (1/10)<sup>10</sup> = 0.00000001%. Like Obama, this ignores the possibility that she has multiple phones or that she doesn't answer personally.
|}

==Transcript==
[Large heading, centered.]

<big>Probability Comparisons</big>

[Left column.]

0.01% You guess the last four digits of someone's social security number on the first try

0.1% Three randomly chosen people are all left-handed

0.2% You draw 2 random Scrabble tiles and get M and M

You draw 3 random M&Ms and they're all red

0.3% You guess someone's birthday in one try.

0.5% An NBA team down by 30 at halftime wins

You get 4 M&Ms and they're all brown or yellow

1% Steph Curry gets two free throws and misses both

LeBron James guesses your birthday, if each guess costs one free throw and he loses if he misses

1.5% You get two M&Ms and they're both red

You share a birthday with a Backstreet Boy

2% You guess someone's card on the first try

3% You guess 5 coin tosses and get them all right

Steph Curry wins that birthday free throw game

4% You sweep a 3-game rock paper scissors series

Portland, Oregon has a white Christmas

You share a birthday with two US Senators

5% An NBA team down 20 at halftime wins

You roll a natural 20

6% You correctly guess someone's card given 3 tries

7% LeBron James gets two free throws and misses both

8% You correctly guess someone's card given 4 tries

9% Steph Curry misses a free throw

10% You draw 5 cards and get the Ace of Spades

There's a magnitude 8+ earthquake in the next month

11% You sweep a 2-game rock paper scissors series

12% A randomly-chosen American lives in California

You correctly guess someone's card given 6 tries

You share a birthday with a US President

13% A d6 beats a d20

An NBA team down 10 going into the 4th quarter wins

You pull one M&M from a bag and it's red

14% A randomly drawn scrabble tile beats a d6 die roll

15% You roll a d20 and get at least 18

16% Steph Curry gets two free throws but makes only one

17% You roll a d6 die and get a 6

18% A d6 beats or ties a d20

19% At least one person in a random pair is left-handed

20% You get a dozen M&Ms and none of them are brown

21% St. Louis has a white Christmas

22% An NBA team wins when they're down 10 at halftime

23% You get an M&M and it's blue

You share a birthday with a US senator

24% You correctly guess that someone was born in the winter

25% You correctly guess that someone was born in the fall

You roll two plain M&Ms and get M and M.

26% You correctly guess someone was born in the summer

27% LeBron James misses a free throw

32% Pittsburgh has a white Christmas

33% A randomly chosen Star Wars movie (Episodes I-IX) has "of the" in the title

You win the Monty Hall sports car by picking a door and refusing to switch

You win rock paper scissors by picking randomly

34% You draw five cards and get an ace

35% A random Scrabble tile is one of the letters in "random"

[Right column.]

39% LeBron James gets two free throws but misses one

40% A random Scrabble tile is a letter in "Steph Curry"

46% There's a magnitude 7 quake in LA within 30 years

48% Milwaukee has a white Christmas

A random Scrabble tile is a letter in Carly Rae Jepsen

50% You get heads in a coin toss

53% Salt Lake City has a white Christmas

54% LeBron James gets two free throws and makes both

58% A random Scrabble tile is a letter in "Nate Silver"

60% You get two M&Ms and neither is blue

65% Burlington, Vermont has a white Christmas

66% A randomly chosen movie from the main Lord of the Rings trilogy has “of the” in the title twice

67% You roll at least a 3 with a d6

71% A random Scrabble tile beats a random dice roll

73% LeBron James makes a free throw

75% You drop two M&Ms and one of them ends with the "M" up so it's clear they're not Skittles

76% You get two M&Ms and neither is red

77% You get an an M&M and it's not blue

78% An NBA team wins when they're up 10 at halftime

79% St. Louis doesn't have a white Christmas

81% Two random people are both right-handed

83% Steph Curry gets two free throws and makes both

85% You roll a d20 and get at least a 4

87% An NBA team up by 10 going into the 4<sup>th</sup> quarter wins

Someone fails to guess your card given 7 tries

88% A randomly chosen American lives outside California

89% You roll a 3 or higher given two tries

90% Someone fails to guess your card given 5 tries

91% You incorrectly guess that someone was born in August

Steph Curry makes a free throw

92% You guess someone's birth month at random and are wrong

93% Lebron James makes a free throw given two tries

94% Someone fails to guess your card given 3 tries

95% An NBA team wins when they're up 20 at halftime

96% Someone fails to guess your card given 2 tries

97% You try to guess 5 coin tosses and fail

98% You incorrectly guess someone's birthday is this week

98.5% An NBA team up 15 points with 8 minutes left wins

99% Steph Curry makes a free throw given two tries

99.5% An NBA team that's up by 30 points at halftime wins

99.7% You guess someone's birthday at random and are wrong

99.8% There's not a magnitude 8 quake in California next year

99.9% A random group of three people contains a right-hander

99.99% You incorrectly guess the last four digits of someone's social security number

99.9999999999999995% You pick up a phone, dial a random 10-digit number, and say 'Hello Barack Obama, there's just been a magnitude 8 earthquake in California!" and are wrong

0.00000001% You add "Hang on, this is big — I'm going to loop in Carly Rae Jepsen", dial another random 10-digit number, and she picks up

[In light grey color and in the lower left corner there is text.]

Sources: https://xkcd.com/2379/sources/

==Trivia==
* In the original comic, "outside" in the 88% probability section is spelled incorrectly as "outide". In addition, the 39% section had "two free throw" instead of "throws".

* The (seemingly unimportant) odds of LeBron James' versus Stephen Curry's free throws, names in Scrabble, and social security numbers refer to [[2002: LeBron James and Stephen Curry]].

* If you were to act out all the M&M-related probabilities, you would draw (or flip) 32 M&Ms in total. In addition, you would draw 8 Scrabble tiles in total for each Scrabble-related probability.

==References==
<references/>

{{comic discussion}}
[[Category:Statistics]]
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