1.  To figure out what the area of a trapezoid means, rearrange it into a rectangle.  Ask what the altitude of the rectangle means, and ask what its width means.  Then ask what it means to multiply those two quantities.

2.  Fractions of bugs are OK.  A fraction of a bug can be interpreted as the probability that the bug will be here, rather than there.

3.  When you cut the triangle from the trapezoid and paste it to the remaining figure to form a rectangle, the triangle fits exactly and forms a perfect rectangle (we are assuming an ideal case, of course, not an actual physical cut).  No area is added to or taken away from the figure, it's just rearranged.  So (assuming the ideal case of exact measurements to start with) the result is exact, not approximate.

4.  You don't need to know what an ergluck is to include it in your units calculations.  If you multiply an ergluck by a frabling you get an ergluck*frabling.  If you divide an ergluck by a frabling you get an ergluck/frabling.  You can't add erglucks to frablings, since the two quantities are not like terms.

5.  sqrt(1960 h) was given with a specific meaning, assuming specific units and giving you a result in specific units.

sqrt(h/5) also had a specific meaning in specific, assuming specific units.

You would have used both of these quantities in analyzing the flow information from the last few days.