Final answer:
The level of measurement for a survey on the average American's shoe size is ratio.
Step-by-step explanation:
The level of measurement that would be applied when doing a survey on the average American's shoe size is ratio. The ratio scale level of measurement provides data that has a definite ordering, can be measured in equal intervals, and has a true zero point. Shoe sizes can be ordered, measured in equal intervals (with a difference of one unit between sizes), and a shoe size of 0 represents the absence of a shoe.