# 2379: Probability Comparisons

(Redirected from 2379)
 Probability Comparisons Title text: Call me, MAYBE.

## Explanation This explanation may be incomplete or incorrect: Created by LEBRON JAMES THROWING M&Ms AT A KEYBOARD. The table for the explanations of the chances isn't complete, nor is the transcript. Do NOT delete this tag too soon.If you can address this issue, please edit the page! Thanks.

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), M&M candies (11), playing cards (9), NBA basketball mid-game victory predictions (9), Scrabble tiles (7), coins (7), white Christmases (7), and the NBA players Stephen Curry and 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 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 psephologist Nate Silver is referenced in one of the list items. On the date this cartoon was published, Nate Silver's website FiveThirtyEight.com was 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 these sources, as mentioned in the bottom left corner.

The title text refers to the song "Call Me Maybe" by 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

Odds Text Explanation
0.01% You guess the last four digits of someone's Social Security Number on the first try There are nine digits in a Social Security Number, but the last four are commonly used as an identity verification factor. (1/10)4 = 0.0001, or 0.01%
0.1% Three randomly chosen people are all left-handed The chances of having left-handedness is about 10%, and 10%3 = 0.1%.
0.2% You draw 2 random Scrabble tiles and get M and M This appears to be an error. Under standard English 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 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.
0.5% An NBA team down by 30 at halftime wins This calculation, along with all related ones, use the source 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 . 0.254≈ 0.39%; 0.2594 ≈ 0.45% . Both are closer to 0.4% .
1% 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%.
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 (1/364)(0.73), for the third (1/363)(0.73)2... Summing all of these from 1 to 365 gives us his total odds of winning at any point in the game are ≈ 1.022% .
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 Backstreet Boy Each of the five Backstreet Boys has a different birthday, so the odds that you share a birthday with one is 5/365.25 ≈ 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 0.019 (1.9%).
3% You guess 5 coin tosses and get them all right The chance of correctly predicting a coin toss is 0.5. The chance of predicting 5 in a row is 0.55, 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 ~3.13% .
4% You sweep a 3-game rock paper scissors series Picking randomly, you have a 1 in 3 chance of beating an opponent on the first try. (1/3)3 = 1/27 ≈ 4% .
Portland, Oregon has a 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 US Senators At the time this comic was published, 15 days were birthdays for more than one Senator, and 15/365.25 ≈ 4%.
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 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. 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 27%. The probability of 2 misses is (27%)2, 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% .
9% Steph Curry misses a free throw Curry's career free throw percentage is 91%, so the probability of a miss is 9%.
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. 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 magnitude 8+ earthquake in the next month Note that, unlike other earthquake examples, this does not specify where the earthquake occurs.
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% .
12% A randomly-chosen American lives in 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 US President Presidents James Polk and Warren Harding share a birthday, and are the only presidents so far (in 2020) to do so. Additionally, 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.)
13% A d6 beats a 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 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 0.92=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% 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% .
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%.
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% Pittsburgh has a white Christmas According to Randall's source, the probability of snow cover in Pittsburgh is 32%.
33% A randomly chosen Star Wars movie (Episodes I-IX) has "of the" in the title Episodes II (Attack of the Clones), III (Revenge of the Sith), and VI (Return of the Jedi) are the movies. This gives the odds of 3/9 ≈ 33% .
You win the Monty Hall sports car by picking a door and refusing to switch The 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
48% 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% 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%)2 = 53.9%.
58% A random Scrabble tile is a letter in "Nate Silver" 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% .
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% 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 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%)2 = 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%)2 = 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% .
87% An NBA team up by 10 going into the 4th 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)2 = 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%
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)2 = 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)5 ≈ 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)2 = 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 magnitude 8 quake in 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)3 = 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)4 = 99.99% .
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 This probability combines two events.

First, the probability that a random 10-digit telephone number belongs to Obama is 1/1010. 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 North American Numbering Plan, the odds of a random number being hers would be 1 - (1/10)10 = 0.00000001%. Like Obama, this ignores the possibility that she has multiple phones or that she doesn't answer personally.