Lets say there is 40% chance that an event will happen. Than it is said that the probability of the event is increased by five times. I do realize that the resulting percentage is not 200% or even 100%.

I do however assume, that the result will be 1 - (1 - 40%) / 5 = 88% (instead of increasing the probability, I decrease the opposite).

Now, is that correct? If not, what formula will calculate the new chance of the event depending on the probability multiplication?

  • 1
    $\begingroup$ I think you're trying to extract a precise meaning from wild hyperbole. Don't waste your time. $\endgroup$
    – dfeuer
    Dec 12, 2013 at 7:32
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    $\begingroup$ I think you'll have to define "increasing the probability by five times" rigorously first before proceeding with your investigation. $\endgroup$
    – Lost
    Dec 12, 2013 at 7:55
  • $\begingroup$ can it be $45\%$? $\endgroup$ Dec 12, 2013 at 9:29
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    $\begingroup$ This is similar to this question $\endgroup$
    – robjohn
    Dec 12, 2013 at 12:57
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    $\begingroup$ I understand what you meant, but with a question like that, you need to be able to define it rigorously in mathematical terms in order to understand it. $\endgroup$
    – Lost
    Dec 13, 2013 at 0:37

1 Answer 1


Using the reasoning in this answer, we get the odds to be $2/3:1$ and $5\times2/3=10/3$. The probability of an event with odds of $10/3:1$ is $10/13=76.923\%$


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