Logical reasoning PrepTest 154 · Section 4 · Question 25

Incorrect. This could be false. We don't know that they're harvesting a greater number of fish, just that they're continuing to harvest a greater percentage of the total amount of fish, by weight, each year. It could simply be that there are fewer fish, but they're the same size.

Incorrect. We don't have any data about the period after 2010, so we can't draw any conclusions about it.

Correct. Argument or Facts:
Facts

Question Type:
Must Be True

Stimulus Summary:
From 1960 to 2010, the commercial fishing industry got better gear every year, and therefore harvested a greater percentage of the total amount of fish, by weight, in the world's oceans each year. From 1960-1994, the total weight of fish harvested increased each year. But from 1995-2010, the total weight of all fish harvested stopped increasing.

Answer Anticipation:
Yikes, poor fish! This is a rare LSAT question that requires a basic understanding of arithmetic, but don't worry, this is pretty much fifth-grade level math. You could plug in some numbers on your scratch paper if you need to, in order to understand this more easily. Let's say each year they harvested 1% more of the total amount of fish than they did the year before. At a certain point, they're going to harvest so many fish there aren't any left. If you remove 99% of the fish from the ocean this year, that leaves 1% to survive into next year and maybe breed. Next year you remove 100% of the fish from the ocean, which is definitely going to be a smaller total number of fish than there were in the ocean last year before you removed 99% of them. So you harvested a higher percentage of all available fish, but less fish by total weight. That's probably what's going on here: they're taking out a higher proportion of all available fish, but the population isn't replenishing each year, so a higher proportion of fish is less total fishweight.

Answer Explanation:
This is what we anticipated. Using the same units (total amount of fish, by weight), this suggests that the total quantity available for harvesting decreased, which would explain why commercial fishing boats can harvest a greater percentage of the total and yet not a greater absolute amount of fish, by weight.

Key Takeaway:
Don't worry, you don't need to do much math on the LSAT. Whenever you run into something like this, if you're stuck on the implied arithmetic part, just make up the simplest example you can think of. In this case, the "harvested 99% last year and 100% this year" example is improbable in the real world, but makes the phenomenon described in this question pretty obvious. It's not really about math, it's about the logical relationship between ratios and absolute quantities.

Incorrect. This isn't necessarily true. It just didn't increase after 1995. It could be exactly the same every year.

Incorrect. This also isn't necessarily true. We're just only looking at data from 1960-2010. There could be a similar phenomenon in earlier data (and probably is—especially if you consider whaling to be part of the fishing industry) but we aren't examining it right now.