Archive for the ‘Probability’ Category

The Chinese Round Table

Friday, August 31st, 2018

One fine evening, Jack and Jill were dining at the Fu Manchu Magic Noodle House, their favorite Chinese restaurant. They sat at a round table served by their regular waitress, Wang Shu.

A number of dishes containing delicious tidbits for plucking off with their chopsticks were situated in front of them on a rotatable round tray.

Jack and Jill sampled the many delectable Chinese morsels to their heart’s content.

“Pick a fortune cookie, Jack,” said Jill, pointing at the decorated cookie jar in the center of the table.

“The cookie says: ‘Good fortune. Soon get special dessert’,” said Jack.

“Hmm,” said Jill, “what does it mean, Wang Shu?”

“Now, special desert,” announced Wang Shu while clearing up after dinner.

Wang Shu placed four dishes containing fried ice cream balls and spicy chocolate truffle balls – delicious Chinese desserts.

In each of the first three dishes there were two fried ice cream balls and eight spicy chocolate truffle balls. The fourth dish contained six fried ice cream balls and four spicy chocolate truffle balls.

“Fortune cookie offer special dessert,” said Wang Shu.

“How generous,” replied Jack.

“Bring it on, Wang Shu,” said Jill.

“Close eyes,” said Wang Shu, “you too,” addressing Jill. Wang Shu spun the dessert tray with the four dishes.

“Please, keep eyes closed and pick one dessert from dish,” said Wang Shu to Jack. Jack picked a dessert ball, which Wang Shu quickly replaced from a large pot containing both dessert types.

Jack opened his eyes and saw a fried ice cream ball melting in his hand, which he promptly ate to his great satisfaction.

“You guess which dish ball from, you no pay. Boss say special promotion,” informed Wang Shu.

“We like that,” said Jill.

Jack scratched his head and then wrote some figures on a napkin, Jill peeping on. Then Jack pointed to a dish.

“Correct dish you choose. Boss say, this time free, next time you pay plenty,” said Wang Shu with a big smile.

Jill was already busy munching away at the balls on the dessert dishes.

“Doggie bag, please,” said Jack.

Was Jack just lucky or had he worked out a probable dish to pick?

Which of the dishes do you think Jack chose?

The Flying Card

Tuesday, August 28th, 2018

At the Lucky Duck casino Nick, the dealer, was sitting at a green felt table and practicing fancy acrobatic shuffles with a deck of cards when suddenly one card flew away and sailed into a nearby plant bed with some petunias and foliage.

“I’ll bet ya 100 bucks you can’t figure out if da card dat just flew away from your deck is a red or a black one,” said Carmine, the floor overseer who happened to be walking by and observe the event.

“You’re on,” said Nick, “on one condition.”

“What’s dat,” replied Carmine with some suspicion.

“That I draw 13 cards from the deck at random,” said Nick.

“Ok, sure,” said Carmine, “no problem, Nick, go ahead an pull dem.”

Nick then drew 13 cards at random from the deck and they all turned out to be black cards.

Then Nick pulled out a calculator, a notepad and a pen and got busy making some calculations.

After some minutes had passed Nick proudly announced: “The card is red, Carmine, go and check it out.”

Carmine walked over to the flower bed and picked up a red card.

“Jeez, Nick, how did ya figger dat out?”

“Give me the 100 bucks and buy me a beer and I’ll tell you all about how to make a pretty sure bet,” said Nick.

 

Can you figure out how Nick knew that the card most likely was a red one?

The Faulty Die

Friday, August 24th, 2018

Jack was sitting at a café table reading a magazine when Jill sat down and ordered some pastries and a hot chocolate.

“What are you reading with such a puzzled look on your face,” said Jill, munching a delicious apple strudel with a flaky crust.

“It’s a puzzle about a guy who is given a bag with 100 dice and told that one of the dice is faulty since it has six dots marked on all of its faces,” said Jack. “Then he is told to reach into the bag and pick one die.”

“So what’s the puzzle all about, then?” asked Jill, taking a small sip of her hot chocolate.

“You’re supposed to work out how many sixes in a row the guy has to throw before he can be 90% sure that the die he is throwing is the faulty one,” said Jack.

“Hmm… since there are 100 dice, it seems to me that you’d have to throw an awful lot of sixes to be sure the die was faulty,” said Jill.

“Maybe,” said Jack, “but we have to give mathematical proof of the solution to the puzzle.”

“What’s the prize?” said Jill finishing off her apple strudel and taking a large sip of her not so hot chocolate.

“Jill, it’s ten thousand dollars for the correct answer,” said Jack.

“What are we waiting for, Jack!! Why don’t you get busy on figuring out the solution,” said Jill enthusiastically, “then we can rent an apartment in Mambo Bay for a great vacation.”

“Hmm…,” said Jack, “’Bay’ gives me an idea.”

Straight vs. Full House

Tuesday, August 14th, 2018

On another fine evening, there was a heated discussion at the Royal Flush Card Club as to how many occurrences of Full House and Straight would occur in the course of 30 throws of five poker dice.

Bing Jones III was betting $100 against Franz Fingerflitzer that he would get at least two instances of a Full House, the latter claiming at least two Straights during the trial – ties leading to a rematch until a winner emerged.

Lots of paper was expended and the whisky flowed freely while members of the Royal Flush Card Club busied themselves calculating the probabilities involved for throwing a Full House and a Straight.

However, accuracy and interest faded rapidly as whisky was poured, and this task was abandoned in favor of registering bets and proposing exuberant toasts, expectations rising to a high pitch, as if prior to a championship horse race.

Who do you think won the bet, Bing Jones III or Franz Fingerflitzer?

The Same Sun Sign

Tuesday, July 31st, 2018

“Jack, I’ll be taking a course in Astrology soon,” said Jill.

“That’s nice,” said Jack, “How many people will be on the course?”

“Twenty-five or so, I was told,” said Jill.

“How many people do you think will be Geminis, like you?” said Jack.

“No, idea. What would you say, Jack?”

Jack told her and it turned out he was pretty right.

What would you say was the number of other Geminis Jill met on the Astrology course?

 

The Deck Split

Sunday, July 29th, 2018

At the Royal Flush card club one evening, there was a lively discussion among its members about splitting a deck of cards into two equal piles after a thorough shuffle, in which, respectively, there would be exactly ten red cards in one pile and exactly ten black cards in the other pile.

Bets were taken for twelve trials to check whether this event would occur at least once.

How much would you bet on this event occurring in the course of twelve such splits?

The Winning Seats

Thursday, June 28th, 2018

The McDuffy Travel Agency was offering special prizes for vacationers to improve its turnover. The advertising stated that the prizes would be determined on the airport bus.

One day there were fifteen vacationers going to the Caribbean island of Buena Siesta for a two week holiday at the Balmy Breezes Beach Resort. Before boarding the airport bus, which seated twenty persons, they were addressed by their charming tour guide Melanie Goodbottom.

“Two of you could win some awesome prizes if you are lucky enough to sit in the two seats with pre-determined prize seat numbers,” explained Melanie Goodbottom waving a clipboard with the passenger list at the entrance to the airport bus, skirt flapping in the wind.

“The winners will receive a week of free dinners for two at any of the best restaurants in Morgan Town, their choice of sightseeing tours for two all over the island and/or scuba diving lessons for two – for those of you who are of the sporty type, of course,” said Melanie Goodbottom enthusiastically, brushing some windblown locks out of her eyes.

The vacationers eagerly thronged towards the airport bus door, climbing over each other to mount the steps of the bus. Those who entered scurried to seat themselves at random, leaving five seats unoccupied for staff.

The bus driver grunted, sitting down at the wheel, and the porter got busy loading luggage into the lower compartments of the airport bus, while Melanie Goodbottom helped pull a number of the more portly passengers up the steps leading to the seating level of the bus.

When all the passengers were finally settled into their lush seats eagerly anticipating the results, Melanie Goodbottom picked up a microphone to announce any winners via the loudspeaker system, and the bus driver switched gears to get the show rolling towards the airport.

What would you say is the probability of two passengers winning these prizes?

 

The Broken Glasses

Friday, March 30th, 2018

At Danny’s Beach Bar run by Danny McDoogle at a popular Andalusian beach, there were five waiters who would take turns washing glasses used by customers.

One day there were five broken glasses, four of them caused by one of the waiters named Pedro.

Danny McDoogle was furious, figuring that this was certainly beyond the realms of chance and due to sabotage. So, he decided to fire Pedro for damaging his property.

The other waiters stood up for Pedro claiming that this could happen to anyone.

Based on probability, would this event be a valid reason to fire Pete for being careless, or could it have been an accidental occurrence as the waiters claimed?

The Twin Birth Rate

Monday, February 26th, 2018

“Did you know that seven pairs of twins are born on average at each of the hospitals in Brownville?” said security guard Barney Coxworth to Hank Burnside, the janitor of the Belleview Hospital.

“Naw, had no idea, Barney. Why is that important?” said Hank, steering his mop bucket into a corner to listen further.

“Well, Hank, I’ll bet you 100 dollars that during the coming month there will be no week at any of the five hospitals in Brownville during which twins are born consecutively on each day of any week,” said Barney.

“Barney, if seven pairs of twins are born every week at each of the five hospitals in Brownville, I figure the stork might just decide to arrive every day now and then.”

“Right you are, Hank.”

“Only makes common sense, Barney,” said Hank,“ so I’ll take you up on your bet.

“With a hundred dollars I could buy a pair of shoes,” said Hank.

“Ok, let’s spit and shake on it and see how it goes, Hank,” said Barney with a poker face.

I wonder who you think will win the bet, and why?

The Dance Academy

Friday, November 17th, 2017

Jean-Pierre was walking down the Rue de la Bonne Chance in Paris one early spring evening when through a large display window he saw many couples dancing in what appeared to be a softly lit dance academy, and noticed the graceful movements of a beautiful young woman.

Jean-Pierre instantly fell in love and walked through a door above which a large, blinking neon-lit sign read: “Chez Antoine de le Boeuf École de Danse” to speak with a registrar.

Jacqueline, the registrar, explained that for each dance lesson ten male students would be lined up at random to face ten female students arranged in a line at random.

The instructor, Madame le Coeur, would push a button on a hand calculator with her long, red fingernail to generate a ten digit number each time a line of students had to be arranged, the students lining up according to their own number.

The eager Jean-Pierre was told he could buy various packages, such as for 7, 14, 21 or 28 lessons.

Jean-Pierre tried to work out how many lessons he would need to be 50% sure of being paired with the enticing woman, he found out was called Emmanuelle, for a dancing session.

Jean-Pierre figured that if the first session package did not work out, he could always buy some more packages.

Which lesson package would you suggest Jean-Pierre should buy to be able to dance with Emmanuelle with a certainty of 50%?

If the first package didn’t work, how many more packages should Jean-Pierre buy to achieve a success rate of 90%?