Logical reasoning PrepTest 148 · Section 1 · Question 2

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Errors in Reasoning

Stimulus Summary:
5 years ago Ð Wilson hair dryers made up 50% of market
Now Ð Wilson hair dryers make up 25% of market
Income/hair dryer hasn't changed
Therefore Ð Wilson's net income for hair dryers is half of what it was 5 years ago

Answer Anticipation:
The stimulus here introduces two key pieces of information related to common flaws. First, there's a timeline, and the argument compares 5 years ago to today. When that happens, your first thought should be that things might have changed in a way that creates a problem for the argument. And while a change—market share went down—and a similarity—income/hair dryer hasn't changed—there could be other relevant changes.

Which leads straight into the second elements that suggests a flaw—the percentages. When an argument uses percentages, be careful that it doesn't jump to discussing amount. Here, Wilson's percentage of the market went down, but the argument concludes that the number of sales therefore went down, resulting in less income. However, that's a flawed jump because of another potentially relevant change from 5 years ago—maybe the market for hair dryers got bigger. If the market doubled, then Wilson's 25% might represent the exact same number of sales, and thus their net income wouldn't have gone down.

No matter which avenue you took to get here—timeline, or percentage/amount—you end up in the same place. The argument assumes that the hair dryer market hasn't increased in size enough to balance out Wilson's declining market share.

Answer Explanation:
This answer highlights the assumption that an erosion in market share means an erosion in net income. However, if Wilson sold the same number of hair dryers in a much larger market, they could lose market share but still make the same income.

Key Takeaway:
When an argument jumps between different times, start thinking about what could have changed in those times. When an argument discusses percentages, there's a good chance that it will invalidly jump to discussing amounts.

These associations are good to start forging between content and errors in reasoning, as they can make spotting the common flaws a lot easier and faster!

Incorrect. First, the stimulus limits itself to discussing net income, not profit. Second, since the comparison is what's relevant and not the specific amount, the argument wouldn't need to specify the exact amount of profit. As we saw here, stating that net income per hair dryer didn't change was enough to prove the conclusion, absent the flaw noted in (A).

Incorrect. The conclusion of the stimulus is about only their hair dryers ("the product" referring back to these hair dryers, not "their products"), so this answer is out of scope.

Incorrect. What happens after Wilson ships the hair dryers is out of scope of the argument since the conclusion is about their net income, not the net income of retailers who carry their products.

Incorrect. First, profitability is out of scope of the argument, which limits itself to discussing net income. Second, even if this answer were about net income, the relative "rank" of it on their products is out of scope of an argument that's about just whether they're making more or less money from that product than they were 5 years ago.