Statistical probability in JavaScript

[torpiler]

Statistical probability wise is 4/5000 the same as 1/1250?

 

[CodeMonkeyJ]

Yup, 4/5000 reduces down to 1/1250. No fancy math needed.

 

[torpiler]

Yup, 4/5000 reduces down to 1/1250. No fancy math needed.

If the chance is a multiple event win would the result remain the same? What of exponential decay in such a case?

 

[CodeMonkeyJ]

I need more context. Is the "multiple event win" reducing the possibilities, e.g., removing a marble from a bag, or are the odds the same each time, e.g., spinning a slot machine (which would be zero decay)? What result are you looking for? The total odds of winning if it was soun multiple times?

 

[torpiler]

I need more context. Is the "multiple event win" reducing the possibilities, e.g., removing a marble from a bag, or are the odds the same each time, e.g., spinning a slot machine (which would be zero decay)? What result are you looking for? The total odds of winning if it was soun multiple times?

Total odds i.e 1/5000 spun four times vs, 1/1250

 

[CodeMonkeyJ]

To combine all four spins into a total probability that at least one win, you use the "at least one rule." First, find the probability that all of them will _fail_. Then, subtract it from one.

P(all) = (1 - 1/5000) * (1 - 1/4000) * (1 - 1/3000) * (1 - 1/2000)
P(at least one) = 1 - P(all) 
P(at least one) = 1 - (0.9998 * 0.99975 * 0.999666 * 0.9995)
P(at least one) = 1 - 0.998717 = 0.00128 = 0.128%

For four spins of 1/1250, it's the same process, but a little more simplified.

P(fail) = 1 - 1/1250 = 1 - 0.0008 = 0.9992
P(at least one) = 1 - 0.9992^4 = 1 - 0.9976 = 0.0024 = 0.24%

 

[torpiler]

To combine all four spins into a total probability that at least one win, you use the "at least one rule." First, find the probability that all of them will _fail_. Then, subtract it from one.

P(all) = (1 - 1/5000) * (1 - 1/4000) * (1 - 1/3000) * (1 - 1/2000)
P(at least one) = 1 - P(all)
P(at least one) = 1 - (0.9998 * 0.99975 * 0.999666 * 0.9995)
P(at least one) = 1 - 0.998717 = 0.00128 = 0.128%

For four spins of 1/1250, it's the same process, but a little more simplified.

P(fail) = 1 - 1/1250 = 1 - 0.0008 = 0.9992
P(at least one) = 1 - 0.9992^4 = 1 - 0.9976 = 0.0024 = 0.24%

Thanks so much for the explanation!

 

[AngleWyrm]

Total odds i.e 1/5000 spun four times vs, 1/1250

Check out my article on Probability, which explains how to use probability in a simple, easy to read fashion, and hopefully entertaining enough to be worth your time.