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.

[7salmonswimming]

You need to be precise with the question you’re asking.

1. What are the odds of me picking the Ace of Spades on Monday, and then again on Tuesday?
   

1. What are the odds of me picking the Ace of Spades on Tuesday having already picked the Ace of Spades on on Monday?
   

Scenario one is two random and unrelated events. 1/20 each time.

Scenario two is a single, multi-stepped event making the odds of a specific outcome slimmer.

You need to ask the question correctly to get the correct answer.

[msmith501]

I thought my coin example was the easiest to understand the difference....

[PotholeParadise]

Here are dice.

Fainne

How many pssible combinations can you make with a throw of two six-sided dice?

How many of those combinations would win you a prize if you could win 100 euro for a matching pair of dice?

[7salmonswimming]

It’s like TTC. What are the odds of having five boys? What are the odds of having another boy when you already have 4 boys?

[Hercwasonaroll]

OP your English is shocking. You can't comprehend the difference between the 2 scenarios you've posted.

If you specify the card that you want repeating over 2 days the odds are 1/400. For example ace of spades followed by ace of spades.

If the exact card doesn't matter but having the card repeated does, the odds are 1/20. This is because there are 20/400 combinations that are repeats. For example ace of spades followed by ace of spades, or queen of hearts followed by Queen of hearts, or 2 of diamonds followed by 2 of diamonds etc until you have all 20 different cards.

[PurpleDaisies]

I don’t think it’s that salmon. The op can’t see the difference between having five of the same and having five of a particular sex.

[Spamantha]

I thought my coin example was the easiest to understand the difference....
Yes, or a 'pack" of cards containing only 2 cards.

But the OP is trolling.

[PotholeParadise]

I did an Advanced Search.

Spamantha has a point here.

[SleepWarrior]

OK, I see my mistakes (thanks @purpledaisies, I am very tired right now!).

What a funny thing to troll about. I can almost see why someone might enjoy setting everyone off on an argument about pushchairs on buses if they like to watch a fight. This is very... niche!

[msmith501]

@SleepWarrior ... niche but what are the odds eh? 😀

[kateandme]

im so shit at this.it makes my brain bleed.and feel really stupid

[SleepWarrior]

@msmith501 I'd say the odds are 1/400 and I won't hear a word otherwise.

@Thepants999 Those odds are 1/20 and to be quite honest I'm shocked that you can't calculate something so plainly obvious for yourself

Fainne - I assume you are in bed and I hope you are having terrible probability related nightmares.

[Supertrooper98]

Fainne you're being embarrassing. Leave it now.

[BarbaraofSeville]

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

FFS^

You're wrong, FFS.

If you don’t specify the first card, and only want the second card to match the first card, it's 1 in 20, because that's not the same question as both cards being a specified card.

First example any card then the same card = 1/1 x 1/20 = 1/20

Second example specified card and then the same card again = 1/20 x 1/20 = 1/400.

Is the maths you do in whichever country you are in different to the UK and the rest of the world?

As we need to declare our qualifications, maths A-level and a scientific degree, professional qualifications and 25 years experience in an industry that requires a good understanding of statistics and the ability to explain it to idiots non specialists.

[Owlsintowels]

purple, I and others are correct.

Fainne either doesn't understand maths, or is a troll.

gavel

My explanation at the beginning of the thread is simple and correct, OP must be trolling to not have understood it. Surely noone can be that dense?

[Lweji]

What I want doesn't change the probability lol
Well... You may want that, but you won't get it because you're wrong. Probability zero.

[ClareBlue]

Fainne, you have an Irish qualification in maths and you are embarrassing everyone who ever took higher level maths. Either that or you are a dick Troll. It has been explained over and over again. If you want a specified card on the first draw it is 1 in 400, if it doesn't matter what the first card is then it is 1 in 20.

[EggysMom]

If you start day one (before pulling out any card) by saying "I want to pick the Ace of Spades", the probability is 1/20.

If you start day one (before pulling out any card) by saying "I want to pick the Ace of Spaces for two days in a row" then the probability is 1/20 x 1/20 i.e. 1/400.

However if you start day one by being happy with any card that you pull, for example, the Ten of Clubs; and then only start day two by saying "I wantto pick the Ten of Clubs again" then the probability of doing this is just 1/20 because day one was a random pick with no probability involved, you were happy whateverthe outcome.

[SoupDragon]

Do you not do Maths in England or something?


That's bloody rude

[LordEmsworth]

The answer is different depending when you ask the question.

Before you draw any card, the chance of you getting the same card twice is 1 in 400.

After you draw the first card, the chance of you getting the same card again is 1 in 20.

There are only 20 cards, each of them has an equal probability of being picked. The fact that you drew the Ace of Diamonds the first time, doesn't influence the second time - it's not that you have a 1 in 400 chance of drawing the Ace of Diamonds a second time and a 19 in 20 chance of drawing any other card.

So based on the way you have phrased your question - "Am I correct in saying that the odds of me picking the same card [today as I did yesterday] is a multiple of the single odds?" - then you are wrong. The chance of you picking the same card today as you did yesterday is 1 in 20.

If you mean "Am I correct in saying that the odds of me picking the same card twice in succession is a multiple of the single odds?" then you are correct, but it's not what you asked!

[Mayorquimby2]

This is one of the great wind ups 😂😂😂

Brilliantly played too
.
Just enough lack of a specificity in the question to draw you in, asking what appears to be the same question in a different way completely changing the meaning multiple times to create a bit of confusion and engagement, and then the irresistible combination of arrogance and stupidity


1/20 btw

Or

20/20 * 1/20

[StatisticallyChallenged]

This is hilarious. OP repeatedly phrases question badly then insults people who answer it. Class

[PotholeParadise]

ClareBlue

you have an Irish qualification in maths and you are embarrassing everyone who ever took higher level maths.

FWIW, I'm happy to assume that it's just her, and not the whole Irish educational system. I've overheard fellow pupils swearing blind to new teachers that our class hadn't covered topics the previous year when I remembered that we had!

You can take a horse to water, but you can't make it drink.

[Mayorquimby2]

I did honours maths (Irish version of higher) and I'm fucking bailing this question


(Did further probability as my option question too. Me 😎 )