It looks like they’re actually tier 1 (they seem to be standing on a white platform), but what, if any, weight is each layer above them? I can see narrow platforms, but are they all taking most of the weight?
I’m not sure whether this was meant as an athletic or purely aesthetic display – since they’re billed as ‘acrobats’, I assumed skill was involved, so what would be the best and worst case scenario those 8-10 in the narrowest tier would be supporting?
e: was there any kind of structural support in this? I’m not finding much about it.
Here’s a Snopes article about this event at the 1980s Olympics in Moscow.
If you do a rough estimation in one unit, you don’t have to do 4 significant figures for the converted units. Just round it to 50kg or whatever, and do your calculations (101*50) in the converted units instead of converting again, so the numbers line up nicely in either unit.