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This is not, actually, much of a rules question, but after much consideration, this still seemed the appropriate forum in which to place this question I have for you all.
At a recent tournament (in which I was not playing) the tournament organizer included a trivia quiz in the overall tournament scoring. Now, this is fine (sop at serious GW run 40k tournaments, if I remember correctly), but I was a little put out by one of the questions.
The question was as follows:
18 Necron warriors fire into the back of a Land Raider which is 8" away. What is the probability that the Land Raider is destroyed.
The question itself is fine, covering a pretty wide range of facts that everyone probably ought to know about the rules as well as specific information about Necrons and Landraiders. What bothered me is that not one person got the question right. Not one--even the tournament organizer, who wrote the quiz, got it wrong.
However, had the question been written a bit differently, most everyone (including the TO) would have had the right answer.
So, I have two questions for you all.
First, what is the probability of those 18 Necrons dropping the land raider?
Second, let's say that one person did get the question right. What would be the appropriate response? To give credit to everyone who got the same answer as the Tournament Organizer, or go with what the actual answer to the question should be?
Hmm, well, I'd reckon to probability such (trying to do it from memory):
18 warriors * 2 shots each = 36 shots
36 shots * 2/3 chance to hit = 24 hits
24 hits * 1/6 chance to glance = 4 glancing hits
4 glancing hits * 1/6 chance to destroy per glancing hit = 2/3 probability of destroying the land raider
I don't have the space-marine codex, so I can't check to see if their raider has any special rules that might affect survivability, but those numbers are right for the chaos raider (unless my math's wrong).
And the appropriate response is, of course, to give credit to the person who got the actual right answer.
thank you and good night
Edit:
That was the answer that virtually everyone came up with at the tournament. It doesn't have to do with special rules on the land raider--it's a math thing...
Oh well.
I agree on the second part, but perhaps this question would be both more meaningful and more relavent:
Everyone got the question wrong. However, people who came up with the answer 2/3 (which is what the TO came up with) were given credit for it despite the incorrectness of their answers. Does this seem to be the appropriate solution?
Last edited by Bean; July 22nd, 2005 at 08:54.
Well, I'll be very interested to hear what the right answer is. At this point, I'm wondering if the t.o. was just too proud to admit that the answer key was wrong, but I'll see what other people respond with.
If I were the scorer, I wouldn't give credit to anyone if no one got the right answer. . . . assuming the right answer is the right answer.
[edit]Or was there some kind of anal math-wonk specification, such as probabilities needing to be expressed as ratios rather than fractions?[/edit]
thank you and good night
Last edited by Holothuria; July 22nd, 2005 at 09:37.
If I were the scorer, I would shoot the guy who came up with the question, the answer above is anaccurate, only slightly but none the less, this is not true probability, probability calaculations SHOULD be done like this:
RULE: you must consider every possible outcome:
Supose one guy fires needing a 3 to hit, then possible outcomes are:
1
2
3
4
5
6
Clearly 3:6 or 1:2
however suppose 2 guys fire, possible outcomes now become:
Guy1 Guy2
1 1
1 2
1 3
1 4
1 5
1 6
2 1
etc,
do the maths and you will find there are 36 possible outcomes, 9 of these are no hits, 18 are one hit and 9 are 2 hits, proability 9:18:9 or 1:2:1
This clearly gets more and more complicated the more people with 18 warriors firing, there are 6^18 possible outcomes which can then be distilled as above into 19 possible results (even needing that 6 for a glancing hit:
0 hits, 1 hit, 2 hits... 18 hits I dont intend to do the maths, but frankly if I was asked this at a tourney I would be rather nonplussed, once you got the ratios of results, you then need to start for each of the results, working out the chance of destroying the vehicle with a glancing hit (you need to consider every possible outcome of the dice rolls for each of the 19 possible results, making it look like 19 times harder than the first set of maths, but in fact, it is closer to 10 times harder.
SIGH, then you multiply the two sets together, and work out the overal probable outcome, without the use of calcularters or algorithms, you are probably talking close to an hours work
On the other had sitting back and raising one finger at the question master is a matter of seconds
Alright, I'll step back in. First, to Cheredanine:
It is a complicated problem, but it doesn't have to be that complicated of a problem to do properly. (Oh, and by the way, if you need threes to hit, you have a 2/3 chance, not a 1/2 chance)
I'm not inclined to post the correct math just yet, I am actually interested to see how people deal with probability questions like this.
Suffice to say that both of your approaches will either yield incorrect results or far, far more work than is necessary. I'll keep checking in on this, but if you want an answer sooner, please feel free to pm me, and I'll talk to you about it in private.
Heh, Cheredanine, you forgot that they're in rapid-fire range--a mighty thirty-six dice to deal with there.
thank you and good night
Bean yeah OK, but point was the approach, as I said, I aint doing the maths, it will take the best part of an hour, but it will give you the correct result
Holothuria, damn your eyes, but you are right, I suspect the guy who came up with the question did not have the same statistics lecturer at Uni that I did!
No, I don't suppose he did have the same stat instructor, but he's not such a bad guy as all that. Actually, he generally runs a good tournament, just messed up this time, thinking that finding the average number of destroyed land raiders (which is what the process Holothuria went through yielded) was the same thing as finding the probability of a single land raider being destroyed--which seems to be a common mistake.Originally Posted by Cheredanine
As for your approach, yes, it does seem that you could get the right answer going about it he way you propose, but a lot of it isn't necessary to get the correct answer.
Bean, please enlighten me why? This approach was the one advocated by said lecturer, I always thought he knew what he was doing (I suspect the University did too, that would explain why they employed him as a lecturer in statistics, although the leather elbow pads on his cardigan and the pipe could also have swung it)As for your approach, yes, it does seem that you could get the right answer going about it he way you propose, but a lot of it isn't necessary to get the correct answer.
Last edited by Cheredanine; July 22nd, 2005 at 11:07.