# Probabilty an event will occur

1. Sep 25, 2013

### cpscdave

If I have an event that on average has occured once every 10 days.
The probablity of that event occuring on any given day is 1/10
so then the probabilty the event occur tommorow 1/10
the probabilty the event will occur within the next 2 days is:
(1-1/10)*1/10+1/10
Pobabilty the event didnt occur on the first day but on the second plus the probabilty the event occured on the first day.
And so on for 3 days, 4 days etc etc etc

Thanks!
-Dave

2. Sep 25, 2013

### Office_Shredder

Staff Emeritus
Assuming the events occur independently of each other (for example, if it happens it is just as likely to happen again tomorrow as usual), then I think your analysis is sound.

Notice you could solve that 2 day problem slightly easier (which makes solving. e.g. the 8 day problem much easier). The probability that it occurs in the next two days is one minus the probability it does not occur. The probability it does not occur in either of the next two days is simply (9/10)2, so the probability it occurs at least once in the next two days is 1-(9/10)2. Not too helpful for in the next two days, but if someone wanted you to find the probability the event occurs in the next 14 days, for example, then this would make your expression a lot simpler.