to ask if you can answer a question re probability (Maths question)

[Fainne]

So, say I have 20 cards in a pack.

I pick one. It's the Ace of Diamonds let's say for argument's sake.

I then pick another one out of the same pack of 20 cards the following day.

Am I correct in saying that the odds of me picking the same card is a multiple of the single odds?

So 1/20 x 1/20 = 1/400

?

Because I've someone telling me the odds are still 1/20 that I'll pull the same card.

Btw - there's absolutely no need for being so insulting to someone, even if you think they're thick as shit.

Wow - pot, kettle, black!

I worded it rather flippantly and carelessly, Purple. It was just that he'd clearly given the odds for drawing a named card that everyone and their sister has given in this thread, and on the way, specified that the odds of getting the same card again would be 1/78 on the second draw.

If the comments on the tarot card site are to be the oracle of truth, OP is still wrong, even by them!

Btw - there's absolutely no need for being so insulting to someone, even if you think they're thick as shit.

The irony! I started to count the number of insults OP had hurled on this thread, but then remembered that I went through the Englsh education system and therefore can't do maths, so...

Btw - there's absolutely no need for being so insulting to someone, even if you think they're thick as shit.

This has to be a joke, right? Go back and look at the way you spoke to people last night - absolutely disgraceful.

There’s no shame in not understanding maths. Probabilities especially can be counter-intuitive. But to speak to people the way you did because you don’t agree with them (even though they’re actually correct) and to not consider that they might have a point is what makes you thick as shite.

Fainne
Since you want to know levels of maths qualifications, I have a level maths and a degree in physics. You have described two different probability problems with two different answers and people have very patiently explained the difference several times. You have then been very rude to them, when in actual fact you are in the wrong.
Either you can't understand the maths involved or you have poor reading comprehension skills or you aren't actually interested in hearing what others say on the matter.
In the words of my Yorkshire grandmother, "Oh do give over!"

"If I'm wrong, I ain't the only one who's wrong!"

Speaking as one who occasionally has to teach probability... how depressingly right you are there.

That's basically the only thing you're right about though. @PurpleDaisies has the patience of a saint.

WTF? This thread cannot be real!

PurpleDaisieshas the patience of a saint.

I agree with this!

Wow, OP you are really digging that hole bigger and bigger. People have tried to explain very calmly and politely why you are wrong and you continued to be offensive.

But logically, I still can't see how the probability of pulling any card is the same as pulling the same card twice.

I'm no maths expert (unlike some on here) but what you said above made me think of it this way.

Pulling 'any' card the first go is 20/20 or 1/1, and then pulling the same card again is 1/20. Multiply those and you get 1/20.

If you're not fussy about which card you pick on day 1 then the odds of getting any card are 20/20
The odds of getting the same card the next day are 1/20
So the answer is 1/20.

If you think of a specific card first, (ace of spades) your chance of pulling it on day 1 is 1/20; and day two is another 1/20 = 1/400.

Before day 1

The chance of pulling out any card on Day 1 is 1, any card will do.

The chance of pulling out the Ace of Diamonds on Day 1 is 1/20.

The chance of pulling out the same card on Day 2 as you did on Day 1 is 1/20.

The chance of pulling out the Ace of Diamonds on Day 2 is 1/20.

Therefore, the chance of drawing the Ace of Diamonds twice in a row is 1/400, but the chance of drawing any card twice in a row is 1/20.

After Day 1.

Whatever you drew on Day 1, that has happened, it's in the past. Suppose it was the Ace of Diamonds. Well that's not a 1/20 chance any more, it happened, so it's now probability 1.

The chance of drawing the Ace of Diamonds on Day 2 is still 1/20.

Therefore, the chance of drawing an Ace of Diamonds on Day 2, given that you already drew one on Day 1, is 1/20.

Pulling 'any' card the first go is 20/20 or 1/1, and then pulling the same card again is 1/20. Multiply those and you get 1/20.

That is a very neat explanation. I will steal that one.
Thanks, St Purple of Daisies

I've not read the whole thread, I gave up at

"Ok.

Let me try to make this simple.

We've got 20 cards. 1 of those is the Ace of Hearts.

I want to get the Ace of Hearts on Day one.

1/20 chance? With me so far?

Day 2.

What are the odds of me getting the Ace of Hearts again?

It's not 1/20. It's 1/400.

FFS."

One thing I gleaned from it though, Purple, I hope you teach, if you don't, you should.

@Fainne sadly you haven't got the answer you want despite deriding those whose mathematics ability is clearly way in advance of your own. May I politely suggest getting a pack of cards and actually trying it out for yourself and report back with the results....

... somewhere there is a village lacking something....

Stick with my coin example from this morning. It's easier for @Fainne to grasp... or apparently not

Thanks to all who said nice things. Perhaps now I have all this good karma I’ll go and be a total arsehole on some other thread.

Anyone know any good grammar ones?

there's absolutely no need for being so insulting to someone, even if you think they're thick as shit.

Says the person who was incredibly rude and insulting first 😂😂

There’s no shame in not understanding maths

Well there bloody well should be. I hate it the way people say "I'm rubbish at maths" and then laugh, as if it's something to be proud of. No one laughs about not being able to read or write. They are ashamed of it.

Not everyone can be an actually, or a chartered accountant, but not being able to grasp basic maths, which this is, is shameful. Anyone can grasp basic numeracy, it just requires a small amount of effort, that they've never put in. Nearly every council will run adult education classes in basic maths. There's no excuse (other than some kind of actual diagnosed learning disability.)

Actuary...not actually....maybe I need English lessons!

"Btw - there's absolutely no need for being so insulting to someone, even if you think they're thick as shit."

There's only one person insulting others on this thread (and their educational system) and that person also does not understand probabilities.

Well there bloody well should be. I hate it the way people say "I'm rubbish at maths" and then laugh, as if it's something to be proud of.

It's a peculiarly English thing, I've found. Instilled by many generations of people pulling down the tall poppies No other country seems to be as suspicious of learning as England. Maybe in the past it actually stood us in good stead, but it's certainly outdated now.

What a dripfeed OP, obviously the rules of cumulative probability change when you are talking about tarot cards rather than a standard deck....