Posted on 05/07/2015 7:27:31 AM PDT by MNDude
I'm trying to figure something out for work, but my math skills are not very good. How do I calculate percentages if an event reoccurs multiple times?
Suppose there is an event that has the chance of occurring on in 6 times (like rolling a dice and getting a "five").
What are the chances I will get a "five" if I roll the dice six times?
Six of those total outcomes contain exactly one "five".
If you're looking for the odds of getting exactly one "five" in six rolls of a die, that would be 6/46656, or .0001286 (to the best of my recollection).
5 1 1 1 1 1
5 1 1 1 1 2
5 1 1 1 1 3
5 1 1 1 1 4...
think you see where this is going.
jewbacca and pelican have the correct formulation, if I understand your question correctly.
1) the probability of throwing a 5 one or more times in 6 rolls is: 1 - (5/6)^6, where '^' is the symbol for exponentiation.
2) the probability of throwing a 5 exactly once in 6 rolls is: 6 / 64, or, reduced, 3 /32, or approx. .0937
For questions like 2), the fastest (probably easiest, too) solution can be found with Pascal's triangle, which for 6 rolls (the 7th line of the triangle) is: 1 6 15 20 15 6 1
Hope that's of some use to you, and FReegards!
Ooooh! That's a very different problem! Now order matters, because a successful "hit" ends the stream of "rolls"!
1000 iterations of rolling up to 6 times, and stopping when you get a "five". Let me think on that one for a bit. Definitely tweaking the dustier parts of my brain for old college courses.
Odds of rolling (at least) one five in n rolls (assuming independence/equal likelihood of rolls) would be => 1 - (5/6)^n. So for six rolls you get 1 - 0.3348 = ~67% chance.
That must be why you’re the teacher and I’m not.
You are not looking to calculate percentage. You want to calculate the odds (or the chances) of something occurring. This involves the use of statistics and depending on the nature of the sample size and the occurrence can be quite complex to calculate. Moreover, you may want to know the correlation values and that gets even more interesting
you haven’t taken a math class recently have you?
Which is known as 1 in 6. Odds are not shown as percentages because that is misleading.
And since the calls stop once he gets a single "five" (a live contact), the odds of subsequent rolls are irrelevant (because they won't waste time calling again).
So the odds of getting at least one "five" in 6 rolls is the 66.52 percent chance LambSlave gave...
Multiply that by 1000 target clients, and it gives you 665.2 likely live phone contacts if you stop at 6 tries, and you have a 16 percent chance of a live contact per attempted call.
Wrong. You apparently missed the posts that state very clearly for dice rolls the answer is independent of previous results. This is not a closed box with balls that are drawn and reducing the opportunity case ( at least not as described by the poster)
5 N N N N N
N 5 N N N N
N N 5 N N N
N N N 5 N N
N N N N 5 N
N N N N N 5
where N is some non-5 outcome of a roll...thus... ...exactly 6 such serial outcomes. Your list confuses permutations with combinations, ok?
Awesome!! That’s they information I trying to figure out. Thank you everyone!
You are in so far over your own head it is not even funny.
That’s correct.
To be picky, though... your 16 percent and your rolling dice comparison is slightly off... 1/6 is actually a 16.66666(repeating) percent, which is what we used for our calculations. If it is really exactly 16.0 percent, and not 16.666666 percent, then your expected final contact number becomes (0.84^6)*1000... or closer to 648.7 contacts. I don’t know if those last 17 live contacts are important or not, but it is the difference between 1/6 and 16 percent.
You are right, however... if looked at as a serial outcome, and he only cares about exactly one "five" and the other five results must all be non-fives, then there are only 6 outcomes out of 46656 outcomes: one where the sole five is in the first slot, the second, the third, etc.
So then, we were asked to provide mathematical information that is intellectually misleading.
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