Had to take an exam to get a license from the EPA for work. This was one of the questions:

>You take a sample from a surface area of 3 inches by 24 inches. The lab reports 300 micrograms of lead on the sample. From which surface must the sample have been taken for there not to be a lead hazard?
>a) smooth floor (threshold is 10 micrograms per square foot)
>b) carpeted floor (threshold is 10 micrograms per square foot)
>c) window sill (threshold is 100 micrograms per square foot)
>d) window trough (threshold is 400 micrograms per square foot)

Am I doing my math wrong, or misunderstanding the question maybe? Seems like every answer is wrong.