I don't think Raoul Duke's example of $667.00 being equivalent to 4000 Yuan was meant to be an accurate guide for someone looking to exchange Yuan for dollars. It should be only deemed a rough guide used to compare the relative lifestyles of FT's in China on 4000 Yuan/month with employees in the U S on 667 US Dollars/month,in truth a difficult comparison to make accurately.
In any case,a FT teaching in China on 4000 Yuan/month would only be allowed to convert a maximum of 30% of his monthly salary into foreign currency, and only on a monthly basis at that.