#3 -

[Jules97]

Hi,

Could someone explain why D is correct? I was thrown off by the percentages and proportions mentioned in the passage (that Chickadees are twice the mass of Kinglets, but Kinglets consume 75% more food than larger birds) and chose C.

Thanks!

[Robert Carroll]

Jules,

You have identified exactly the area of the passage that contains the information to answer this question. It says there that kinglets would have to consume 75% more food per unit of body mass than the birds twice their mass. We don't need to do the specific math here - comparing kinglets to those larger birds, kinglets just have to consume more food per unit of mass. Answer choice (D) just requires us to know that it's more, not exactly how much more (although the passage does give us that info!).

If we want specific numbers to illustrate what the author seems to be saying, let's say a kinglet is 100 grams in mass. That would make a chickadee 200 grams. Let's say a chickadee needs 1 calorie per gram of body mass to maintain its temperature. Kinglets would need 1.75 calories per gram of mass to maintain THEIR temperatures. I don't really want to, or need to, engage in any more calculations here - kinglets need more energy per unit of mass (grams was the unit of mass I chose here) to maintain their temperatures. The total amount of energy is not at issue here. Answer choice (D), and line 20 of the passage, are both ratio-based ideas - energy unit per mass unit.

Robert Carroll