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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?

AgentFire
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    I think you're trying to extract a precise meaning from wild hyperbole. Don't waste your time. – dfeuer Dec 12 '13 at 07:32
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    I think you'll have to define "increasing the probability by five times" rigorously first before proceeding with your investigation. – Lost Dec 12 '13 at 07:55
  • can it be $45\%$? – the_candyman Dec 12 '13 at 09:29
  • @Lost I do not very strong in math, however I'll try: by another meaning, the chance of that the event will happen is **five times** more likely than before. – AgentFire Dec 12 '13 at 12:48
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    This is similar to [this question](http://math.stackexchange.com/q/465718) – robjohn Dec 12 '13 at 12:57
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    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. – Lost Dec 13 '13 at 00:37

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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 $10/13=76.923\%$

robjohn
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