Rodents are small, gnawing mammals

Answer choices

1. A

   Too Strong: most species6% picked this

   Most species of North American mammals have chisel-like

   We know that rodents have chisel-like incisor teeth, but we're also told that most species of NA mammals aren't rodents. If we knew that most species were rodents, we could infer this answer.

   6%
2. B

   Correct70% picked this

   In North America, rodent species tend to have more individual members than other species

   Why this is right

   This is giving us the mathematical inference we predicted: if most species are not rodent, but most individuals are rodent, then there must be more rodents per rodent species than there are non-rodents per non-rodent species. If most of the vehicles at a drive-in were trucks, but most of the people at the drive-in arrived in a car, then you could infer that there tended to be more passengers per car than there were per truck.

   Skill tested: Most Supported · how this choice captures the argument's function is the move to repeat next time.

   70%
3. C

   Unknown Group3% picked this

   Most species of mammals that have chisel-like incisor teeth can be found

   We don't have any information about 51% or more of "mammals with chisel-like incisor teeth". We know about most "NA mammal species" and most "NA individual mammals", and those are the only most groups we know about.

   3%
4. D

   Too Specific: the single #1 highest19% picked this

   Of the mammal species in North America, the one with the most individual members is

   In each of our two math metaphors so far (male/female tables at restaurant ... or people who came to the drive-in via truck vs. car), we only know something about the overall average. We can't get as specific as one specific table, one specific vehicle. It could be that the table with the most people at it was a male-table, but all the other male-tables only had two dudes, whereas the female-tables were averaging like 5 per table. It could be that the vehicle with the most passengers at the drive-in was an unsafe pickup truck carrying 15 people in the flatbed, but all the other trucks just had 2 passengers, whereas the cars were averaging like 5 people per vehicle. In other words, there can definitely be an outlier among males / trucks / non-rodents. Our inference is only about the overall total vs. number of groups, so our inference has to be expressed as an average of individuals per group.

   19%
5. E

   Unknown Group2% picked this

   Most nonrodent mammal species can be found in

   We don't have any information about 51% or more of "nonrodent mammals". We know about most "NA mammal species" and most "NA individual mammals", and those are the only most groups we know about. You can't ever derive a fact about "most X" if you were never told a fact about "most X".

   2%