Logical reasoning PrepTest 103 · Section 3 · Question 19

To prove that not all categories have seen a decrease in injuries, the argument needs to raise only a single example. As such, there’s no need to discuss other categories of injuries if it successfully shows that knee injuries have gone up. And before you start to think about how the total amount and percentages and math work to see if maybe there’s something to this answer, stop! There will be no question on the LSAT that requires that level of math.

A single cause can have disparate effects, so this answer doesn’t even describe a cause. For instance, ice cream causes us to be happy and it causes ice cream headaches.

The conclusion is that some categories of injury have increased over the past 20 years. There being more skiers would only serve to support that conclusion, as with more skiers, even a decline in percentages of injuries could result in an increased number of injuries. As such, this isn’t something the argument ignores.

This answer describes a Percent vs. Amount flaw, so it’s the correct answer. The argument uses the increase in percentage of knee injuries (from 11% to 16%) as if it rules out a decrease in knee injuries to reach the conclusion that there’s at least one category of injuries where the total amount went up.

The argument doesn’t proceed as if there was a decrease in injuries in each category, let alone that that total could be greater than the decrease overall.