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![[Post New]](/s/i/i.gif) 2017/06/19 22:20:15
Subject: Odds of making a 9" charge with re-rolling one or both dice
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Spawn of Chaos
Texas
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With the release of 8th edition, I see myself needing to make a lot of 9" charges (not 8", as you to set up more than 9" away). I also noticed that re-rolls let you re-roll one or both dice. I've not seen the math worked out on that problem so I worked it out:
Probability of a 9" charge, no re-rolls = 10/36 (27.7%).
If you can only re-roll both dice the odds go to 10/36 + 26/36 * 10/36 = 47.8%
The first part is the success of getting a 9" charge on the first roll. The second part is the probability of failing your first rolling combined with making it on your second.
Now, if you can choose to re-roll one or both of your dice, you have to figure out where the sweet spot is on re-rolling one vs. both. Simply put you should keep any dice that are 4 or greater (unless you rolled two 4s, then keep one). This is because the chance of getting a 5 or 6, if one die is a 4 (1/3) beets the probability of a success if you re-roll dice (10/36).
The math gets tedious but for instance if you rolled a 4 (1/6) that was part of an unsuccessful roll (1/6 * 2/3), you have a 1/3 chance of making the re-roll succeeding (1/6 * 2/3 * 1/3). If you do this for all available options, then you end up with a 52.5% chance of success. It surprised me that this is only about 5% better than only having the option of re-rolling both dice.
Edit: Clearly, I'm better at math than English.
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This message was edited 2 times. Last update was at 2017/06/20 00:15:21
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![[Post New]](/s/i/i.gif) 2017/06/19 22:48:31
Subject: Odds of making a 9" charge with re-rolling one or both dice
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Infiltrating Broodlord
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gratz on doing mathhammer
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![[Post New]](/s/i/i.gif) 2017/06/19 23:50:07
Subject: Odds of making a 9" charge with re-rolling one or both dice
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Junior Officer with Laspistol
Manchester, UK
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I was bored a week ago and just worked out every result. My totals matched yours, so yay!
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This message was edited 1 time. Last update was at 2017/06/19 23:50:21
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![[Post New]](/s/i/i.gif) 2017/06/19 23:59:30
Subject: Odds of making a 9" charge with re-rolling one or both dice
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Spawn of Chaos
Texas
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Trickstick wrote:I was bored a week ago and just worked out every result. My totals matched yours, so yay!
Wait! What if we're both wrong?
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![[Post New]](/s/i/i.gif) 2017/06/20 00:02:26
Subject: Odds of making a 9" charge with re-rolling one or both dice
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Screaming Shining Spear
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I just copied and used your homework....so mine matched yours too!!
Hope I still get a good grade...even if I don't understand it lol Automatically Appended Next Post:
oh no!!! there goes my test scores!!! I hate when cheating fails
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This message was edited 1 time. Last update was at 2017/06/20 00:03:44
koooaei wrote:We are rolling so many dice to have less time to realise that there is not much else to the game other than rolling so many dice. |
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![[Post New]](/s/i/i.gif) 2017/06/20 01:53:52
Subject: Odds of making a 9" charge with re-rolling one or both dice
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Inquisitorial Keeper of the Xenobanks
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But you need a ten inch charge.
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![[Post New]](/s/i/i.gif) 2017/06/20 02:01:39
Subject: Odds of making a 9" charge with re-rolling one or both dice
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Mutated Chosen Chaos Marine
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Nope. Nine. You need to make it to within an inch with the new rules, not base to base.
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Help me, Rhonda. HA! |
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![[Post New]](/s/i/i.gif) 2017/06/20 02:11:28
Subject: Odds of making a 9" charge with re-rolling one or both dice
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Lieutenant General
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No you don't. You only need to be within 1" of the enemy to make a successful charge. So a 9" charge is more than enough to get you within 1" of the enemy.
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'It is a source of constant consternation that my opponents cannot correlate their innate inferiority with their inevitable defeat. It would seem that stupidity is as eternal as war.'
- Nemesor Zahndrekh of the Sautekh Dynasty Overlord of the Crownworld of Gidrim |
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