I want to calculate a half-life string based on the following
I have a 8-day half-life
Day 1 the value is 200
Day 8 the value is 100
Day 16 the value is 50
Day 24 the value is 25
and so on .........
what is the formula to calculate all the days in between the known values?
Last edited by Pepe Le Mokko; 09-16-2019 at 11:57 AM. Reason: Thread title
So 8 day half life.
To calculate... let's say 7 days value.
=EXP(-LN(2)*7/8)*200
=109.0508...
You can validate it by using known #.
Ex: =EXP(-LN(2)*16/8)*200 = 50
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I did it for you this time. Please read forum rules. Thx
A simple google of excel gives you lots of answers
however you are wrong as the 200 should be at day 0 not day 1
=200*0.5^(A1/8) where A1 is the number of days
And if you want to calculate how many days to go from one value [A] to [B].
Use this:
=(LOG(A/B)/LOG(2))*8
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Modytrane
With half-life in B1 and the start value in B2 (which is really for Day 0), then put days 1, 2, 3 etc. down column A starting in A3, then you can have this formula in B3:
=$B$2*0.5^(A3/$B$1)
Copy down as required.
I've done this in the attached file, and used Conditional Formatting on column B to highlight where the multiple half-lives appear.
Hope this helps.
Pete
EDIT: Oops, a bit late to the party on this one !!
perfect thanks. I know this seems super simple to all of you but it is not for me. appreciate your help
Not sure who you are responding to, but glad to help.
If that takes care of your original question, please take a moment to select Thread Tools from the menu above and to the right of your first post in this thread, and mark the thread as SOLVED.
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Pete
very cool thanks.!!
Based on your last post it seems that you are satisfied with the solution(s) you've received but you haven't marked your thread as SOLVED. If your problem has not been solved you can use Thread Tools (located above your first post) and choose "Mark this thread as unsolved".
Thanks.
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