fandomhigh | MATHS CLASSES: WEDNESDAY 26.10

MATHS CLASSES: WEDNESDAY 26.10

Charlie is surrounded by a stack of old books, crumpled pieces of paper, and pencils. He's writing eagerly on one of the blackboards. The heading he's written is: Probability Calculation: Migrasjon.

He waits until everybody in a group has arrived. "Joan Girardi and Kimberly Shaw are no longer enrolled in this class ~~and have possibly been eaten~~. This means that there's an open place in Intermediate, if you know of anyone who might wish to join us.

This is the attendance I have counted thus far, please let me know if I have made any mistakes." He gives them all a copy of their attendance record, as well as todays problems.

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"Pretty sure it's multiply," Angelus said.

"Okay, so..."

[1 in 6] x [1 in 6] = [1 in 36]

"The odds are the same? That just doesn't seem right. Did we miss something?"

"We had to," Angelus said. "No way does the prof give us a puzzle that's that clear cut. Plus I know that's not it. I've played dice more times than most people have had hot dinners and I'm telling you my money's on A. It's like firing a gun, I couldn't tell you the physics but I sure as hell tell you if it's going to hit the target."

Angelus tilted his chair back. He folded his arms and rocked the chair as he thought. "Okay, picture it. We're in Vegas - you ever been to Vegas?"

Lily smiles at his confidence. "No - I've heard of it, though. Somewhere out West, right?"

"Never?" Angelus asked. "Oh no. We've got to fix that. You'll love it. Draco too. Heck, we should make a field trip out of it. Get the gang together. You guys can't be doing anything for Thanksgiving, right? You're British."

"Never," she said. "If it's as great as you say, I would love to go, and Thanksgiving would be the perfect time." Lily started to get excited about the prospect of getting off campus.

"We will make this happen," Angelus started to write some names down on a blank space in his notebook. "I'll send an email out to everybody. Road trip. We can take a plane or - " He paused, thinking about it " - hey, can Draco teleport stuff? You know, with magic? Bel can but I'm thinking a group this big might be too much for him."

Lily thought for a moment. "Well, there was a floo network set up in England - travel by fireplace... I know Draco can apparate, but that's just for himself or possibly one person at a time. We could always try a portkey, but I'll have to ask him if he knows the spell for creating one. We'll come up with something. Oh, Angel! This is going to be amazing!"

"This is going to be the best," Angelus promised her. He was grinning with excitement too. "Trust me, I was there when they built the place and it's only gotten better. We'll get in some gambling, see some shows - Cirque Du Soleil, need I say more?"

Lily laughed. "Well, you could explain to me what 'Cirque Du Soleil' is, for a start."

"It cannot be explained, it must be seen," he promised her. He made a note to buy everyone tickets for a show. "Yes. Excellent. God I'd send us all there this weekend if it wasn't for the stupid Parents' thing. Not that I'm not thrilled Darla is in town but - okay, getting ahead of myself here. I'm sure we're supposed to do some math before the bell rings." He grinned at her.

"Okay," he tapped his pencil against his desk. "So we're in Vegas. We're at the craps table. Draco's there, he's ready to roll, he's asking you to blow on his dice for good luck..."

"Right, math," she said. "I'm in Vegas, blowing on the dice... though I'm not sure what good that will do in terms of bring luck..."

"It's traditional," Angelus said. "Gotta have your woman blow on the dice. You'll crap out otherwise."

Angelus paused as something occured to him. "That's it. That's what we're forgetting. Not the odds if we win, the odds if we lose."

"You've lost me," Lily said.

"We're focusing just on the general odds of them ever getting the numbers," Angelus said, becoming more animated as he figured it out. "What we're forgetting is that the bet is that they get the numbers first."

He started to write out the possibilities on a fresh piece of paper. "See, A says he can roll 12 first. B says he can roll 7 first and second. More important, they're betting against each other. In games like that you don't just win if you win, you win if the other guy loses. And our boy B has more chances to lose because he stupidly bet on two 7s in a row. There's more odds of him not getting those double 7s than there are for A to get the 12 once."

"Wait, but isn't that still the same thing? - I mean, we did the math," Lily says getting frustrated. "The odds of winning for both are one in thirty-six. The odds of losing for both are thirty-five in thirty-six. I feel like I see what you're saying, but I don't."

"The odds of losing look like they're the same but they're not," Angelus said. He wrote more numbers down. "Look, if the first roll is 12 our boy A takes the pot, right? 1/36 odds of happening. But here's the thing, if neither 7 nor 12 comes up, A still has a nice pile of cash to take home to his lady. A wins because B loses and that has - " Angelus frowned as he tried to do the math in his head. "29/36 odds of happening. I think.

"And that's just that one roll. Let's say our boy B has good luck and rolls 7 first time around. If the second roll isn't a 7 and is maybe even a 12 then A's eating steak for dinner again. A's chances of winning stack up higher when you take into account not just the 12, but all the time it's not 7."

Lily almost got what he was saying, but it just wasn't completely clicking yet. "Right... and at least the 12 has some chance of winning on every next roll, where the 7 only has a chance of winning after a 7 has just been rolled..."

"Exactly," Angelus said. "Though it's not as obvious as flipping the odds of B winning. It's figuring out the odds of A winning on 12 combined with the odds of B losing those 7s. Get those and we'll have our answer."

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MATHS CLASSES: WEDNESDAY 26.10

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