calcule target value and % based on increased volume

hi,

I am try to predict targets for a month for jobs that fail

example : -
every day a random amount of jobs are completed on our system (volume) some fail (failures) we calculate from these volumes percentages that represent traffic lights set at certain percentages.

1,So if there are no failures we show the conditional format colour green on the cell showing the calculated percentage.
2, if 10% of the current volume fail we show that cell as yellow.
3, if 30% of the current volume fail it goes red

thats ok but i am trying to calculate the volume we can fail by in each catergorgy before it rolls over into the next section.

So each day the volume increases x amount can fail and we use the formula to get the percentage.

a b c d e f
Expected Minimum Total Failed count Total
Jobs 95.50% 90.50% 42 1 97.62%

=(D31-E31)/D31 (formaul is in f)

so how many more fails can i get before i pass the expected 95.50% and then how many before the Minimum of 90.50%. i have manully change the figures "e" to 2 and 4 to get the results but i want a formula to predict these because the volume is constantly changing.

I'm sure Solver or Goal Seek could be used, but they are a little difficult to automate.

% calculations are usually pretty simple algebra. %success=#success/total Solve for #success #success=%success*total So if I want to know how many successes gives me a 90% success rate #success=0.9*total. In your case, because you probably can't visualize a "partial success" you would need to round the result up to the nearest integer (ROUNDUP function).