IF Epic Percentage done = average of all linked Task Percentage Done

[vishu b]

Hi,

we have a requirement there is a field name with "Percentage " in task,
sub-task & Bug and another field with name "Epic Percentage".

Now when I link issues to epic , can we sum all linked issue and Percentage in epic field.

Example: 

   Task-1 Percentage is 0.5

   Task-3 Percentage is 0.8

   Task-8 Percentage is 1.0

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Now Epic percentage(0.5+0.8+1.0)/3 need to display number 3 dynamically .if we link 5 issues it need to sum with 5.
Please help out on this we are using groovy & Calculated fields.

Thank in advance.