Math question, I think it is called exponential growth, but here is the problem:
Event X has a Y% chance of occurring over the course of a day. This Y% chance is constant and remains at Y% per day.
What formula could I use to determine what the percentage is, overall, for Event X to occur sometime within Z days?
Thanks!
You should hit F5, because chances are I've edited this post at least 5 times.
Example of Array Formulas
Click the * below on any post that helped you.Originally Posted by Jacc
Hi
With the percentage in A1 and the number of days in B1Formula:
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Richard Buttrey
RIP - d. 06/10/2022
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Oh. Well that was simple. lol
To add a little complexity to it in case someone has a similar problem;
If I wanted to display the percentage per possible length, how could this be achieved?
Start 25%
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I'm marking as solved since the original question was indeed answered, this one is just a bonus!
Hi,
The formula is exactly the same. i.e. in C2 copied down (given your example table)
=1-(1-A2)^B2
For illustrative purposes, I am going to change percent to probability. Say for example that each day during a summer week there is a 33% chance of rain. The first thing that I am going to do is to change the percent to a probability, so there is a one in three or 1/3 probability of rain each day. This means that there will be a 2/3 probability that it will not rain. During a week there would be a 2/3 * 2/3 * 2/3 * 2/3 * 2/3 * 2/3 * 2/3 = (2/3)^7 = 0.05853... probability of no rain. Using the complement we can then say that the probability of rain at least one day during the week will be 1 - 0.05853 = 0.94147 which we can then change to 94%. If the probability of Event X is placed in cell A1, then the formula =1-(1-A1)^7 can be used to express the probability that Event X will occur on at least one day during the week. If result over a different number of days are desired, then the 7 would need to be changed accordingly.
Indeed. That's what the formula I gave you does.
[.... deleted; too many typos ....]
If I wanted to display the percentage per possible length, how could this be achieved? [....]
Please Login or Register to view this content.If 25% is in A2 and that is the probability for 1 day, I think the formula in A3 should be:
=1-(1-$A$2)^B3
Copy A3 into A4:A5 or more.
Richard, I only saw your very correct answer after I had posted.
Alternatively, enter =1-BINOMDIST(0,B2,25%,0) into A2 and copy down into A3:A5 and more.
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