Incorrect production calculations?

[Marbles]

Hello,
While testing my factory's peak production power I noticed something off, when I calculate my peak iron plate production I get a different number than the production stats tell me on a peak test.
I have 36 electric furnaces on production power 5, thats 36*5=180 production power. Divide that with the iron plate production time, 36*5/3.5 and multiply that by 60 for plates/minute.
36*5/3.5*60=3085.
When I test I get peaks of 4200 plates a minute.

Same with the ec's, I have 12 tier 3 assemblers, 12*1.25=15 production power, divided by 0.5 and multiplied by 60:
12*1.25/0.5*60=1800 ec's a minute
When I test I get a peak of 2200 ec's a minute.

Is my math wrong or am I missing something?

[DaveMcW]

I noticed this too. I don't think the time lengths are accurate. It's even worse for 5 seconds, and better for 10 minutes.