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kanawa



Joined: Apr 14, 2020

Post   Posted: Jun 03, 2020 - 07:14 Reply with quote Back to top

I had a last turn were I could score choosing between:

1. A single roll: 2+
2. A double roll: 1+

In normal situation I would assume that is the same in terms of possibilities (correct me if I am wrong) but I had a re-roll available. So I was doubting if the re-roll changes the situation and it's better to have a re-roll in a single roll or, considering that if I fail one of the 1+ rolls, the re-roll would be more effective.

Is there any calculation of probabilities in this case?
Suppurax



Joined: Jun 09, 2007

Post   Posted: Jun 03, 2020 - 07:22 Reply with quote Back to top

a 3+ with rr a) is better than a 2+ without rr b).

p(fail for a) ) = 2/6 x 2/6 = 1/9 hence p(success for a) ) = 1 - 1/9 = 8/9

p(success for b) ) = 5/6 < 8/9
kanawa



Joined: Apr 14, 2020

Post   Posted: Jun 03, 2020 - 07:36 Reply with quote Back to top

Thank you. I explained myself wrongly. (1+ doesn't make sense)

My question was: having a re-roll... is better a single 3+ or twice 2+?
ArrestedDevelopment



Joined: Sep 14, 2015

Post   Posted: Jun 03, 2020 - 07:41 Reply with quote Back to top

2+2+ is better with a team reroll.
It's about 93% overall.
The 3+ dodge is 89% or so.

If you had dodge for the 3+, but no team reroll available for 2 gfi for example, you would make the dodge (89% with dodge rr vs 70% for 2+2+ with no reroll).

This may interest you - http://www.elyoukey.com/sac/ it's best to memorize common situations though!

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almic85



Joined: May 25, 2009

Post   Posted: Jun 03, 2020 - 07:43 Reply with quote Back to top

I'm not sure I understand your question.

Is 1. a single roll that passes on a 2+ and 2. is two consecutive rolls that each pass on a 1+?

Seeing as a "natural" roll of a 1 nearly always fails under the rules you are better off only making a single 2+ roll rather than two 2+ rolls.

For 1. your chance of success is 5/6 + (1/6x5/6) = 30/36 = 1080/1296

For 2 your chance of success 30/36*30/36 = 900/1296

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Sharper



Joined: Nov 22, 2006

Post   Posted: Jun 03, 2020 - 07:46 Reply with quote Back to top

A 3+ dodge is 66.66%, 88.89% with RR

A 2+ dodge is 83.33%, 97.22% with RR

2 2+ dodges are 69.44%, 92.59% with RR (94.5% with dodge and RR)


So 2 2+'s dodges are a very small bit better.
Tripleskull



Joined: Oct 12, 2003

Post   Posted: Jun 03, 2020 - 07:50 Reply with quote Back to top

kanawa wrote:
Thank you. I explained myself wrongly. (1+ doesn't make sense)

My question was: having a re-roll... is better a single 3+ or twice 2+?


2*2+ is better then 3+ both with and without a Reroll.

You have the right intuition about spreding te risk on more dice if You have a reroll but in the example it is better even without the reroll.

This is the tool You are Looking for:
http://www.elyoukey.com/sac/
Chivite



Joined: Sep 04, 2017

Post   Posted: Jun 03, 2020 - 09:48 Reply with quote Back to top

The elyoukey calculator is great. Spetially for a long sequence with multiple players involved. For simpler turns or situations i use an app called blood bowl probability calculator, found it free on the playstore
kanawa



Joined: Apr 14, 2020

Post   Posted: Jun 03, 2020 - 11:57 Reply with quote Back to top

Thank you all guys!
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