Gabby and Dustin like food

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Two young mathematicians discuss the eating habits of their cats.

Check out this dialogue between two calculus students (based on a true story):

Devyn: Yo Riley, I was watching my two cats Gabby and Dustin eat their dry cat food last night.
Riley: Cats love food! It’s so weird that they swallow the pieces whole!
Devyn: I know! I noticed something else kinda funny though: Both Gabby and Dustin start and finish eating at the same times; and while I gave Gabby a little more food than Dustin, less food was left in Gabby’s bowl when they stopped eating.
I wonder, is there is a point in time when Gabby and Dustin have the exact same amount of dry cat food in their bowls?
Riley: Hmmmmm. Do Gabby and Dustin both start and finish drinking their water at the same times? And does Gabby start with a little more water than Dustin, and finish with less water left than Dustin?
Devyn: Yes!
Riley: Interesting. I wonder, is there is a point in time when Gabby and Dustin have the exact same amount of water in their bowls?

Is there a time when Gabby and Dustin have the same amount of dry cat food in their bowls assuming:

They start and finish eating at the same times.
Gabby starts with more food than Dustin, and leaves less food uneaten than Dustin.

You might want to try drawing a graph of this situation.

Is there a time when Gabby and Dustin have the same amount of water in their bowls assuming:

They start and finish drinking at the same times.
Gabby starts with more water than Dustin, and leaves less water left in her bowl than Dustin.

You might want to try drawing a graph of this situation.

Within the context of the two problems above, what is the difference between ‘‘dry cat food’’ and ‘‘water?’’

If we write the amount of dry cat food as a function of time, this function is not continuous. The reason it isn’t continuous is that the dry cat food is a collection of individual kibbles, which are eaten whole.

On the other hand, if we write the amount of water as a function of time, this function is continuous.

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