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Author Topic: A Quick Maths Question  (Read 237 times)

Sean Clark

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A Quick Maths Question
« on: November 11, 2019, 10:37:10 AM »
I'm rubbish at maths.

Probability question:

If I roll 2 dice, what are the odds of rolling a 1 on either of the dice? I understand the odds of rolling two 1's ( 1 in 36?) But I could do with knowing the odds for rolling a 1 on one of the two dice.

My line of thinking continues....is it a lower probability than 1 in 6, i.e. rolling one dice where the chance of a 1
is 1 in 6.

Sorry if this makes no sense. I was far better in the Humanities.

Sean Clark

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Re: A Quick Maths Question
« Reply #1 on: November 11, 2019, 10:42:43 AM »
Here is my attempt

1 in 6 (chance of rolling a 1) ◊ 5 in 6 (chance of rolling anything other than a 1) = 5 in 36 OR 1 in 7.2

This has made my head hurt.

Stewart 46A

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Re: A Quick Maths Question
« Reply #2 on: November 11, 2019, 10:58:13 AM »
Sorry Sean cant help, in my experience the chance of rolling any number increases/decrease with the need or not of sed number.

Colonel Kilgore

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Re: A Quick Maths Question
« Reply #3 on: November 11, 2019, 11:09:05 AM »
I propose that it's 11/36 = 31% on the basis that there are 36 different combinations, of which 11 involve a "1" being scored on one and/or other of the two dice.

No doubt Martin will come along shortly and set us all right!

But I do think Stewart has the real answer.

Sean Clark

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Re: A Quick Maths Question
« Reply #4 on: November 11, 2019, 11:39:23 AM »
You see, that sounds much better Simon!

Sean Clark

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Re: A Quick Maths Question
« Reply #5 on: November 11, 2019, 11:45:39 AM »
And helps me with some some design work too.

So if there is a rules mechanic where you want the odds of a 1 coming up to slowly increase each time you roll....

1st roll (giving best chance not to roll a 1):

Roll 2 Dice and count the highest roll.

2nd roll (slightly more chance of a 1)

Roll 1 Dice and keep the result

3rd roll (most likely to roll a 1)

Roll 2 Dice and count the lowest roll.

This is for an article I am working on for the '15 mill'

Nick

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Re: A Quick Maths Question
« Reply #6 on: November 11, 2019, 01:00:06 PM »
Yes, the chances of at least a 1 appearing on the roll of two dice is 11/36.

These calculations are easier to work out by finding the chance of it not happening, i.e.
The chance of the first die not being a 1, is 5/6
The chance of the second die not being a 1, is also 5/6
Multiply them together and the chance of not seeing a 1 on either dice becomes 25/36.
Therefore the remainder, 11/36, must be the chance of a 1 coming up at least once.

Nick

martin goddard

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Re: A Quick Maths Question
« Reply #7 on: November 11, 2019, 01:13:20 PM »
Simon has it spot on.
11 of the 36 outcomes include a score of 1. The reason it is 11 and not 12 is that one outcome has a double 1.
The best of considering this is to write out the 6x6 grid giving all the outcomes of 2D6.

Of course if you roll the D6 one at a toe and the first score matters then all changes.

Leman

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Re: A Quick Maths Question
« Reply #8 on: November 11, 2019, 02:42:58 PM »
Sorry to sound so heartless, but I really donít care. What you roll is what you get. Now back to saving humanity from itís own crass stupidity.

Sean Clark

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Re: A Quick Maths Question
« Reply #9 on: November 11, 2019, 02:53:43 PM »
Thanks then your input Leman.

Leman

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Re: A Quick Maths Question
« Reply #10 on: November 11, 2019, 04:43:25 PM »
I know, completely useless, but numbers hurt my head.

Sean Clark

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Re: A Quick Maths Question
« Reply #11 on: November 11, 2019, 04:56:10 PM »
Me too! But you can't escape them. As the saying goes, the only certainty in life is death and taxes.

Leslie BT

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Re: A Quick Maths Question
« Reply #12 on: November 11, 2019, 06:29:03 PM »
Sean, no such thing as a quick question particularly if it involves maths, just look at 'B' that was simple and it involved maths.