Archive for the ‘Probability’ Category

Picking a High Card

Saturday, February 23rd, 2019

Jake, now a full club member, was back again at the Happy Valley Card Club on a cold and snowy Friday evening.

As usual, there were many people standing around a large rectangular table by the bar, where Charlie, the dealer, was busy having someone pick a card from a pack on the green surface.

“What’s the game this evening, Charlie?” asked Jake, rubbing his cold hands together.

“Well, Jake, you pick a card from the deck. If you get a high card you pay me ten dollars, otherwise you win as many dollars as there are pips on the card,” said Charlie.

“By high card I assume you mean a Jack, Queen, King or Ace?”

“You got it,” said Charlie, “wanna play?”

“Ten dollars seems a bit much, Charlie, but I’ll give it a try to see how it goes,” said Jake.

“Suit yourself,” said Charlie.

After ten games, how much would you say Jake won or lost on average?

The Four Card Deal

Wednesday, February 13th, 2019

Jake dropped by the Happy Valley Card Club to see what was happening on a snowy winter’s Friday evening in December. Jake enjoyed the conviviality and high-spirited discussions about the probabilities of card games in the lounge by the bar.

Jake saw a large gathering around a large rectangular table, where Charlie was dealing cards on the luxurious green felt cover, Christmas music sounding enchantingly in the background.

“What’s the game this evening, Charlie?” asked Jake.

“It’s a variation of the game of the other day. It is called the ‘Four Card Deal’,” said Charlie. Half of your winnings will go to our university scholarship Christmas charity.

“Sounds fine to me. How does this ‘Four Card Deal’ work,” said Jake.

“Well, my man, you pay me 10 dollars and I shuffle and deal four cards face up. I also pull a card from the top of a stationary deck I don’t shuffle,” explained Charlie.

“Very interesting, but what’s the idea?” said Jake.

“If the four cards all have a different suit and no two the same value, you win. But if I pull an ace from the other deck, you lose,” explained Charlie.

“What’s the prize?” asked Jake.

“You win twenty dollars, but if you don’t win and I pull no ace, I repeat the procedure,” said Charlie.

 “Ok, Charlie, let’s give it a go,” said Jake.

How long would you say this game continued on average until Jake won or lost, and what could be any amount Jake paid to charity after playing ‘Four Card Deal’ ten times?

The Three Cards

Wednesday, January 30th, 2019

There was excitement again at the Happy Valley Card Club one Saturday afternoon. People were gathered around a table where a dealer was dealing three cards from a deck face down on the table, then, a bit later, three cards face up.

Jake was curious and approached the dealer.

“How’s this game work, Charlie?” asked Jake.

“Well, you bet five dollars, then I shuffle and lay three cards face down on the table, after which you guess what the suits of the cards are,” said Charlie.

“You mean like two clubs and a heart, or three spades, or two diamonds and a club, and so on?” asked Jake.

“That’s right, Jake. If you guess the suits correctly, then you win ten dollars,” said Charlie.

“If your guess is wrong, then I’ll shuffle and lay down three cards face up. If there are no aces among the three cards, then you get another chance to guess the next three cards I deal face down for free,” said Charlie.

“Hmm, sounds interesting. Let’s give it a go,” said Jake.

After 10 rounds of arriving at a win or ace face up in this game, how much money would you say Jake won or lost?

The Colorful Tennis Doubles

Sunday, January 20th, 2019

The Happy Valley Tennis Doubles Tournament was being sponsored by the Bronson Multi T-shirt Company, Inc. which was supplying free T-shirts in three colors, red, gold and blue, that were dispensed free at random by a machine in the lobby.

Having been informed of this, Calvin and Jude were discussing the various combinations of T-shirt colors the players could appear with.

“I’ll bet you 100 dollars that there will be at least two players among the four players with a red T-shirt on the court within three double team changes,” said Calvin, taking a large bite out of his hot dog.

“Well, I say that two players will show up with one T-shirt color and two players with a different T-shirt color within five double team changes,” said Jude, fishing out another potato chip.

“Ok,” said Calvin, “whichever of these occurs first, wins 100 dollars, plus pays the bill at the restaurant celebration later.”

“Hmm… Ok, deal,” said Jude and shook on it.

Who would you say is most likely to be paying the restaurant bill later?

The Wine Tavern

Monday, December 24th, 2018

One Saturday evening in late winter, Jason, Melanie and Bob were sitting around a cozy table at the newly opened Bacchus Wine Tavern, that was promoting a novel wine pouring system consisting of five different types of wine and a random wine selector.

“Considering this new wine pouring system, what do you guys figure is the probability that we two get an identical wine in each of our glasses and Melanie gets one with a different wine type?” said Jason with an impish, quizzical grin.

“Good question,” replied Bob, “let’s see how it goes after we’ve gone through some rounds,” he suggested with eager anticipation.

“By that time, I don’t think any of us will be able to figure it out,” laughed Melanie, and hailed a waiter to bring the first set of triple glasses.

What would you say is the probability that Melanie, gets a glass of wine that is different and Bob and Jason get the same wine?

About how many rounds do you figure would be needed for Melanie to get her odd glass of wine?

Two Bridge Hands

Friday, November 30th, 2018

One early and sunny Sunday afternoon at the Royal Banana Plantation Bridge Club, there arose an animated discussion as to whether hand A consisting of five clubs, four hearts, three diamonds and one spade was more probable than hand B with four spades, four hearts, four diamonds and one club.

Murphy Smythe thought that hand A would be more probable since there were more clubs. Sally Witheroak said that hand B was more certain as there were many fours and only one club.

The members of the Royal Banana Plantation Bridge Club took sides and split up into two contentious groups, each respectively supporting Smythe’s or Witheroak’s view. This led to multiple impassioned speeches that stretched into the early evening.

The argument was finally settled by Lenny, Sally Witheroak’s little son – who had a scientific calculator in his backpack – after Lenny arrived with his father to fetch mother home to make supper.

What would you say was more probable, hand A or hand B?

 

Days Off

Thursday, November 29th, 2018

“I heard you have a new job, Dirk,” said Barney, taking a sip of his beer.

“Yea, I do, Barney, and it’s a really great job because I get a lot of time off to go fishing at the lake,” said Dirk Burton, master electrician, with a big grin on his face.

“Tell me all about it,” replied Barney – all ears.

“I’m working standby 24/7 for Acme Hot-Plug Electronics, Inc., a large company with many branches. They have an average of seven emergencies per week that they want me to handle,” explained Dirk, gulping down a large swig from his tall mug of beer.

“But that’s crazy, working 24/7. How do you get any time to go fishing?” asked an incredulous Barney, downing a big swig too.

“No problem, Barney. As the number of emergencies to be handled is logged by midnight, the next morning they let me know by 8 am via SMS how many there are for me that day. If they don’t need me, I get the day off,” explained Dirk, ordering another beer.

“I get it. You could get up to seven emergencies in a day, or none at all,” said Barney.

“That’s the deal,” said Dirk, “with no emergencies reported, I hang up my ‘GONE FISHING’ sign on the front door and head for the lake. From there I check the phone until they need me.”

“Wow, that’s the life,” exclaimed Barney filled with admiration, and finishing his beer, “got any fish for sale?”

Can you work out the probability that Dirk will have at least three days off during any week?

How many weeks, on the average, do you think Dirk would have to work to experience one single day with seven emergencies?

The Forgotten Hat

Saturday, October 27th, 2018

It was well known amongst his colleagues that professor Ambrose Helleborus would leave the house and later return without his hat, as a matter of fact, according to his housekeeper, Mrs. MacGillicuddy, this would regularly occur once after every four excursions on the town.

On a windy winter’s day, professor Ambrose Helleborus went to the university library to do some research on the legendary Kingdom of Agartha, after which he went to enjoy a tasty lunch at the Chez Antoine café, whereafter he spent a leisurely afternoon with cronies at the Jolly Hills Chess Club.

Subsequently, professor Ambrose Helleborus returned home without his hat, facing extensive interrogation by Mrs. MacGillicuddy, who would have to retrace his steps and retrieve the hat, as it was a treasured gift from professor Einstein.

But Mrs. MacGillicuddy didn’t mind as she by now had developed a circle of chat friends along professor Ambrose Helleborus’ usual excursion routes.

What are the respective probabilities that professor Ambrose Helleborus left his hat at the university library, Chez Antoine’s and the Jolly Hills Chess Club?

 

The Road Crossing

Tuesday, October 23rd, 2018

Seymore, a green frog, wanted to cross the road to get to his favorite pond where frog mates were plentiful. However, the road was a dangerous place to cross, and Seymore was worried he might get run over by a passing motor vehicle.

Brer Rabbit had told Seymore that on the average about a 100 cars would pass per hour along this stretch of road, which was valuable information indeed.

Seymore needed one minute to hop across the road and any car passing by could be fatal.

So he looked up at his lucky star and got ready to jump.

What would you say is the probability that no car would pass while Seymore was crossing the road and destroy his froggy dream to arrive at his favorite mating pond?

The Chess Match

Monday, October 22nd, 2018

One Sunday afternoon, a chess match was being held at the King’s Hills Chess Club where bets were being made on Henry MacDuff versus Melvin Longspur. Henry MacDuff was rated as a three times better player than Melvin Longspur.

Judge Roy Bean decided that they would play ten rounds and whoever won three consecutive times would win a copy of the famous Royal Diamond Chess set.

How many rounds would have to be played for Henry MacDuff to have a good chance of winning three consecutive games?


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