# How to simply increase probability of an event?

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?

• I think you're trying to extract a precise meaning from wild hyperbole. Don't waste your time. Dec 12, 2013 at 7:32
• I think you'll have to define "increasing the probability by five times" rigorously first before proceeding with your investigation.
– Lost
Dec 12, 2013 at 7:55
• can it be $45\%$? Dec 12, 2013 at 9:29
• This is similar to this question
– robjohn
Dec 12, 2013 at 12:57
• 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, 2013 at 0:37

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 $10/13=76.923\%$