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Orrex

(66,527 posts)
Thu Dec 4, 2025, 10:27 AM Thursday

Statistics/Math Question

In my tool bag I have nine black Sharpies and one silver Sharpie.

If I need a black one and I reach into my bag blindly to grab one, what are the odds that I’ll get the silver one every single damn time?

Of course, if I want the silver one, I’ll blindly draw all nine black ones first.

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Statistics/Math Question (Original Post) Orrex Thursday OP
Ah Yes..I've had this action quite more than a few times. chouchou Thursday #1
The only thing I remember from the one statistics course... 3catwoman3 Thursday #2
It depends. The Madcap Thursday #3
Good question Orrex Thursday #4
Yeah, what you need to do is "sample without replacement" GopherGal Thursday #6
I would... 2naSalit Thursday #5
That's not a statistics question, that's a Chaos Theory question... malthaussen Friday #7

chouchou

(2,689 posts)
1. Ah Yes..I've had this action quite more than a few times.
Thu Dec 4, 2025, 10:47 AM
Thursday

You'll pick the black ones IF you also hit the Power-Ball jackpot twice on the same day.
You are Welcome!

3catwoman3

(28,392 posts)
2. The only thing I remember from the one statistics course...
Thu Dec 4, 2025, 11:24 AM
Thursday

…I was forced to suffer thru is the bigger the N the better, and the smaller the p the better. That’s it.

If I wanted to make sure I got the silver pen, I would just cheat and open my eyes.

Orrex

(66,527 posts)
4. Good question
Thu Dec 4, 2025, 12:07 PM
Thursday

Generally I get the silver on the first pull, keep it in hand, and am certain to draw a black one on the second pull. But if I were to return the silver one to the bag, I’d draw it again 100% of the time.

GopherGal

(2,761 posts)
6. Yeah, what you need to do is "sample without replacement"
Thu Dec 4, 2025, 02:43 PM
Thursday

If you keep returning the one you draw back to the bag, your odds remain the same for each draw. So what you need to do is set aside the one you drew until you get the one you want. In statistics this is called an "urn problem" Of course, the probability calculations by statisticians don't incorporate the Murphy's Law effect that dictates the 100% rate of getting the less desired color...

2naSalit

(99,388 posts)
5. I would...
Thu Dec 4, 2025, 12:11 PM
Thursday

Grab as many as I could and see if the silver one is there in my hand. If not there, grab the rest of them so I would say the answer is 2. (As confirmed by Ray Magliottzzi, the answer is 2).

malthaussen

(18,354 posts)
7. That's not a statistics question, that's a Chaos Theory question...
Fri Dec 5, 2025, 02:15 PM
Friday

... or, really, a Murphy's Law question, and the answer is "every damn time."

-- Mal

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