Georgia Tech professor and mathematician Matt Baker explains the answer to 'Cheryl's birthday' problem that . July 16, August 15, and August 17. The latest viral puzzler to stump the Internet started out as a question for students in Singapore. Cheryl gives them a list of 10 possible dates: May 15, May 16, May 19 June 17, June 18 July 14, July 16 August 14, August 15, August 17 Cheryl then tells Albert and Bernard separately the month and the day of her birthday respectively. To clarify: Both Albert and Bernard want to figure out Cheryl's birthday. May 15 May 16 May 19 June 17 June 18 July 14 July 16 August 14 August 15 August 17 Cheryl then tells Albert and Bernard separately the month and the day of her birthday respectively. So from Albert's statement, Bernard now also knows that Cheryl's birthday is not in May or June, eliminating half of the possibilities, leaving July 14, July 16, Aug. 14, Aug. 15 and Aug.. If it is 16, the answer is July 16. July 16 August 15 August 17 Albert then says, "Now I know Cheryl's Birthday." If Albert was told August, he still would not be sure. Note: What follows is a complete description of the logic for the remainder of the puzzle. . Our task is to represent the problem statements as facts or rules so that we can arrive at the correct answer. The New York Times reported that the head-scratcher was originally posted to Facebook by Singaporean television host Kenneth Kong. At the beginning of the puzzle, this is unknown to Albert and Bernard (and us as spectators). If. Hence, the month that Albert knows doesn't contain either 18 or 19. Cheryl then tells only to Albert the month of her birthday, and tells only to Bernard the day of her birthday. He has also hidden a fun little nugget -. Cheryl gave the pair 10 possible dates. It is either 14 or 16. You have to find Cheryl's birthday. Albert has therefore deduced that the possible dates are July 16, Aug 15 and Aug 17. But, if Cheryl told Albert that she was born in July, Albert could know with 100% certainty that Cheryl was born on July 16th - it's the only July date left! Can you explain the answer to the "Cheryl's Birthday" puzzle that has been sweeping the Internet? Now A can rule out 14, otherwise B could not know the date. (And Albert and Bernard are aware that she did so.) Mike Hartley came up with a novel. You can make such a puzzle. Let's assume Alice, Bob and Charlie are given a set of 3-tuples, one 3-tuple is chosen from the set and they are told the first, the second, and the third elements respectively. Sum and Product Puzzle 'When is Cheryl's birthday?' How to answer that viral math question from Singapore. The problem, which was crafted for a math olympiad test for high schoolers, involves some seriously heavy logic. Origin. Eliminating 14, 16 is the only date remaining in July but 2 more dates remains in Aug leading to ambiguity. Based on the above Albert has worked out that Cheryl's birthday is one of the following: July 16 August 15 August 17 If Albert now knows for certain when Cheryl's birthday is he must have been told the month of July, as if it was August there would be two possible options. Write a computer program to deduce, by successive elimination, Cheryl's birthday. The third and last thing to do is analyze the last piece of data, which is Albert saying that he now also knows Cheryl's birthday. The ten possible dates are x in the chart below. Recently a puzzle that asked the birthdate of Cheryl got popular with the answer of July 16, in which Bernard and Albert have to figure out. Then Cheryl whispered in Albert's ear the month and only the month . Here's full details on the puzzle. The problem was soon posted on Twitter and Instagram, and soon the whole world was flummoxed. The answer is. After Bernard speaks, saying he knows the birthday given that information, it eliminates August from being a contender since. . The question seems simple all you need to do is work out Cheryl's birthday, based on three statements and with just 10 possible dates to chose from but the logic to solving it will really . A school maths question posted on Facebook by a Singaporean TV presenter has stumped . Cheryl's birthday is July 16. May 15, May 16, May 19 June 17, June 18 July 14, July 16 August 14, August 15, August 17 Cheryl tells Albert the month and Bernard the day. Cheryl's list of birthdays. 2. Cheryl's Birthday " Cheryl's Birthday " is a logic puzzle, specifically a knowledge puzzle. Task. Instead, she gives the two a list of ten different dates, saying that one of these dates is her birthday. 2) Bernard: At first I don't know when Cheryl's birthday is, but I know now. It doesn't take a genius to figure this one out. University of Groningen Jonathan Welton Abstract We present four logic puzzles and after that their solutions. June 17 . Cheryl gives them a list of 10 possible dates. Since Bernard knows Cheryl's day of birthday, in order for. If it is 15, the answer is August 15. There is simply no end to the number of ways the . Albert: Then I also know when Cheryl's birthday is. Cheryl thought a second and said, "I'm not going to tell you, but I'll give you some clues." She wrote down a list of 10 dates: May 15, May 16, May 19 June 17, June 18 July 14, July 16 August 14, August 15, August 17 "My birthday is one of these," she said. Cheryl first gives them a list of 10 possible dates: Cheryl then tells Albert and Bernard separately the month and the day of her birthday respectively. The first step to the solution was to rule out the whole months of May and June because both these months contain unique dates that would give the answer right away. The logic question posted by Mr Kong is now known as 'Cheryl's Birthday'. When is Cheryl's birthday? June 17, August 17. . May 15 May 16 May 19 June 17 June 18 July 14 July 16 August 14 August 15 August 17 Cheryl then tells Albert and Bernard separately the month and the day of her birthday respectively. Cheryl does not reveal the date of her birthday. The students were asked to answer a seemingly simple question: "When is Cheryl's birthday?" To figure it out, you're provided with some vague clues. Solution by Logic Programming In the first clue, Cheryl provides a list of 10 possible dates to both Albert and Bernard. We can eliminate: August 15, August 17 The third statement reduces our options from 3, to the final date. Here's how to solve 'Cheryl's birthday' math problem. A global math Olympiad problem has gone viral on Facebook. 73 and 64. (Advanced) Cheryl's Birthday Puzzle. Well, Albert said he knew when Cheryl's birthday was, therefore he must have been told July. Bernard knows before Albert's last statement because he sees the number. Cheryl's Birthday Puzzle Mathemagic Explanation & Exhaustive Algorithm First, I do not understand how there could be just one date, given the insufficient constraints of the problem. I know that various online outlets have discussed the answer as well; here are the respective solutions presented by The Guardian and The New York Times (don't click those links until you think about the problem for yourself). 3) Albert: Then I also know when Cheryl's birthday is. That leaves only 3 possible days: July 16, August 15, and August 17. Albert's last statement can only be true if Albert sees the month July (else, he wouldn't know). An early version of Cheryl's Birthday, with different names and dates, appeared in an online forum in 2006. Answer to Puzzle #48: When is Cheryl's Birthday 48. These dates can be naturally represented by the following dataset: Our strategy will be to define a view that captures the candidate dates that satisfy a clue as it is revealed to us. May 15, August 15. He's since revealed that the question was actually set for 14-year-olds in the Singapore and Asean Math Olympiads, but it hasn't stopped people from trying to tackle it. If Albert was told one of these month, then there is a possibility that Bernard might know the answer . May 16. If Albert is told month M and Bernard day D, then Albert can simply tell Bernard M , after which Bernard tells Albert D. This is perfectly consistent May 15, May 16, May 19 June 17, June 18 July 14, July 16 August 14, August 15, August 17 Then Cheryl whispers to Albert the month, and only the month, of her birthday. If it is 17, the answer is August 17. Albert and Bernard have just become friends with Cheryl, and they want to know when her birthday is. Bernard not able to determine Cheryl's birthday out of the. As A knows the answer now, it must be July and can not be 14. July 16 May 15, May 16, May 19 June 17, June 18 July 14, July 16 August 14, August 15, August 17 Albert is told one of the months May, June, July, or August. So he must have been told July. Cheryl gives them a list of 10 possible dates. Extra points: a playful aspect of the Cheryl birthday problem was that the answer - i.e. Cheryl's Birthday Puzzle Cheryl's Birthday Puzzle Albert and Bernard just became friends with Cheryl, and they want to know when her birthday is. Good Answer: When I said day, I meant date. When is Cheryl's Birthday? Cheryl tells Albert and Bernard separately the month and the day of her birthday respectively. First, Cheryl says that her birthday is one . The combinations are made up of four possible months and dates falling between 14 and 19. 4 x 6 x 6. They need to figure out what the 3-tuple is. Joseph Yeo designed 'Cheryl's Birthday'. May 15. Here is the problem: You have Albert, Bernard and Cheryl. Albert: I don't know when Cheryl's birthday is, but I know that Bernard does not know too. Cheryl gives them a list of 10 possible dates. Problem: It is known that Cheryl's birthday is one of the following 10 dates listed in the table. Paul is given the product. (Otherwise, we have no challenge to solve.) May 15, May 16, May 19. Yesterday's answers: STEAMY CHALICE GO LIVE DRAG RACE DILEMMA 4 days ago; It's #wordplaywednesday! Cheryl gives them a list of 10 possible dates. May 16, July 16. 16 x 3 x 3. Albert and Bernard now have the following conversation: June 17. Albert: I don't know when Cheryl's birthday is, but I know that Bernard does not know too. Cheryl gives them a list of 10 possible dates. Kenneth Kong. If Bernard . There are only two dates 18 and 19 that uniquely determine the birthday. Cheryl's Birthday problem was a question in a recent Singapore Maths Olympiad. May 15,May 16,May 19,June 17,June 18,July 14, July 16,August 14,August 15,August 17. 1) Albert: I don't know when Cheryl's birthday is, but I know that Bernard does not know too. Here only the final statement by Paul reveals the actual numbers. Therefore the answer is July 16. 10 possible dates provided, the day must not be unique. The "Cheryl's Birthday" problem has attracted a lot of press, with CNN, the Washington Post, Slate, and the Telegraph and countless others weighing in. The text of the entry was as follows: . A fact from Cheryl's Birthday appeared on Wikipedia's Main Page in the Did you know? Related task. May 15 16 19 June 17 18 July 14 16 August 14 15 17. Cheryl's birthday - is also Dr Yeo's birthday. 14 April 2015. Since Albert knows the month, we can eliminate August, because if he were told that the month was August, he won't be able to know the precise date: August 15 or August 17. Cheryl says "my birthday is one of these ten. While this narrows down the field, most would have found that there're still a set of possible answers: Then the puzzle will work, and have a unique solution. Albert knows the month. Paul, Sam and Dean are assigned the task of figuring out two numbers. Cheryl gives them a list of 10 possible dates. So, after all that work, we've come to the conclusion that Cheryl's birthday is July 16 th July 14, August 14. Video Ad Feedback. Line 3) Albert: Then I also know when Cheryl's birthday is. Therefore, Cheryl said July to Albert and 16 to Bernard. The logic puzzle When her two new friends Albert and Bernard wanted to know her birthday, Cheryl tells them a list of 10 possible dates for her birthday but not the actual birthday. She gives . For him to now know, he must have been told. Rather than telling the two when her birthday is like a normal person she gives them a series of dates. Cheryl gives them a list of 10 possible dates. Cheryl gives them a list of 10 possible dates. May 15, May 16, May 19 June 17, June 18 July 14, July 16 August 14, August 15, August 17 Cheryl then tells Albert and Bernard separately the month. Bernard knows the. When you write it down . So the answer is: July 16 is Cheryl's birthday They get the following information: . Cheryl's birthday is the title of a math problem that has stumped millions after going viral this week. So she gives her friends Albert and Bernard a list of 10 possible . Albert knows: Cheryl's birthday is in July.