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<blockquote data-quote="Gez" data-source="post: 2241217" data-attributes="member: 1328"><p>Three shots with a 20% chance to hit for each shot results in:</p><p>20% × 20% × 20% chance of all three hitting, so 0.8% of triple damage.</p><p>(20% × 20% × 80%) + (20% × 80% × 20%) + (80% × 20% × 20%) of two of the shots hitting, so 9.6% of double damage.</p><p>(80% × 80% × 20%) + (80% × 20% × 80%) + (20% × 80% × 80%) of one of the shots hitting, so 38.4% of single damage.</p><p>80% × 80% × 80% of none of them hitting, so 51.2% chance of no damage.</p><p></p><p>So, you the average damage will be: </p><p style="text-align: center">(51.2×0 + 38.4×1 + 9.6×2 + 0.8×3)/100</p><p></p><p>Which amounts to 0.6. A 60% chance of dealing single damage, and 40% chance of missing altogether, would yield the same statistical average damage.</p><p></p><p>Indeed, three separate 20% chance of something happening is not the same as a single 60% chance of said thing happening... But that's because you're reasonning in a binary mode, either it happens, or it doesn't. D&D is more quantitative than that, either it doesn't happen, or it does, in a varying number of occurences.</p><p></p><p>Similarly, if you have only two attacks but with a 30% chance to hit (+10 is equivalent to +2 on a d20), then, what do we see?</p><p>30% × 30% of double damage (09%).</p><p>(30% × 70%) + (70% × 30%) of single damage (42%).</p><p>70% × 70% of no damage (49%).</p><p style="text-align: center">(49×0 + 42×1 + 9×2)/100</p><p>Which amounts to... 60% again...</p></blockquote><p></p>
[QUOTE="Gez, post: 2241217, member: 1328"] Three shots with a 20% chance to hit for each shot results in: 20% × 20% × 20% chance of all three hitting, so 0.8% of triple damage. (20% × 20% × 80%) + (20% × 80% × 20%) + (80% × 20% × 20%) of two of the shots hitting, so 9.6% of double damage. (80% × 80% × 20%) + (80% × 20% × 80%) + (20% × 80% × 80%) of one of the shots hitting, so 38.4% of single damage. 80% × 80% × 80% of none of them hitting, so 51.2% chance of no damage. So, you the average damage will be: [center](51.2×0 + 38.4×1 + 9.6×2 + 0.8×3)/100[/center] Which amounts to 0.6. A 60% chance of dealing single damage, and 40% chance of missing altogether, would yield the same statistical average damage. Indeed, three separate 20% chance of something happening is not the same as a single 60% chance of said thing happening... But that's because you're reasonning in a binary mode, either it happens, or it doesn't. D&D is more quantitative than that, either it doesn't happen, or it does, in a varying number of occurences. Similarly, if you have only two attacks but with a 30% chance to hit (+10 is equivalent to +2 on a d20), then, what do we see? 30% × 30% of double damage (09%). (30% × 70%) + (70% × 30%) of single damage (42%). 70% × 70% of no damage (49%). [center](49×0 + 42×1 + 9×2)/100[/center] Which amounts to... 60% again... [/QUOTE]
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