How do i calculate a relative percentage out of 3 other percentages?

Im creating an application which handles projects and tasks. Each project consists out tasks. Now i want to calculate how far the project has progressed based on the progress of the tasks. So lets say i have a project with 3 tasks with. 30%, 60% and 90% progress. What is now the overall progress? I think i've slept too much during math!How do i calculate a relative percentage out of 3 other percentages?
.3+.6+.9=1.8/3=.6 or 60%
60%How do i calculate a relative percentage out of 3 other percentages?
You can't calculate the overall progress unless you know the relative lengths of each of the tasks.

When you know that then you can take the weighted average of the percentages.



If all tasks have the same length then you can just take the average:



(30 + 60 + 90) / 3 = 60%



If you know that task 1, 2 and 3 take respectively 2 3 and 6 units of time then you could take the weighted average:



(2*30 + 3*60 + 6*90) / (2+3+6) = 70.9 %
the 3 percentages: A%, B%, C%

the overall percentage: (A+B+C)/3

replace 3 with the number of tasksHow do i calculate a relative percentage out of 3 other percentages?
you can take the average of the values of %progress in each task

overall progress = (30+60+90)/3

=180/3 = 60 %
It all depends on the importance of each task in the overall project. For example,



If, say, task A represents 50% of the project, task B 30% and task C 20%, then you overall progress is

30%*50% + 60%*30% + 90%*20%

= 15% + 18% + 18%

= 51%.



If all three tasks represent 1/3 of the project, only then can you simply take the average of 30%, 60% and 90% which is 60% (first answer).
It depends on a few things. You could just average the percent of the tasks but that would be unreal. You could do a weighted average based on the percents completed and how long each one takes since they will probably be of different lengths. In reality though, most projects are serial operations. You can't do task B until Task A is done so just playing with averages is unrealistic. There you need to look at the project as a whole. Why not just pick up an exiting applications that handles it all .... PROJECT or some other existing software/
If all tasks have an equal weight,(ie, they are all as important to the whole project), you could easily just take the average percentage of the three...

30 plus 60 plus 90 = 180, divided by 3 to get the average of 60...



If you need to also consider the importance of the tasks in relation to each other, or how long they take, just multiply the numbers by a magnitude of relative importance before you average them... (I would suggest actually using division on the less important tasks until a set point for the most important of the three... (But when the most important task equals 100%, remember to put an "IF" statement in the loop to ensure that at some point the divisors are removed so that the average can be accurate as "total task completion" equals 100%.)



(If the 30 job is most vital to the project, you would want to ensure that the lack of progress in that area is more loudly reflected in your outcome... so, 30 plus (60 * .75) plus (90 * .80) equals 49% (showing that until the most important task (30%) is closer to completion, it will drive the percentage average lower.
add the percents and divide by three



30 + 60 + 90 = 180 / 3 = 60%



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