Physical Percent Complete(%) calculations don't match.

Summary:

Physical Percent Complete(%) calculations don't match.

I entered 1,000,000 as Planned Cost in one task and activate Baseline Planned.

Next I import 500,000 cost that is Planned Resources from AP.

Then I generated Burden Cost, 5 Burden Costs of 10,000 each generated .

Actual Cost is 550,000 and Planned Cost is 1,000,000, so it is supposed to be 55% but  it turned out to be 52.38..%.

Why wasn't it 55%? How was it calculate?

Please let me know.

Thanks,

Mayuko