It could work something like this:

Number Each Basket from 1 to 10.

Select 1 Apple from basket 1
Select 2 Apples from basket 2
etc..

You will now have (1+2+...+10) = 55 Apples

If they all weighed 4 oz, then the scales would show 55x4=220 oz.

But if the weight was, say, 225 oz, then you would know that there 5 apples that weigh an extra ounce, so the basket with the heavier apples must be basket 5.