Logical reasoning PrepTest 139 · Section 4 · Question 18

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Errors in Reasoning

Stimulus Summary:
High-end computers (over $1k) - 13% profit
Low-end computers (under $1k) - 25+% profit
We only have so much floor space, and we'd sell as many low-end computers as both combined if we only sold them, so that's what we should do to maximize profits.

Answer Anticipation:
There's a lot of math going on in this stimulus, but whenever there's a percentage mentioned, there's a good chance that the argument is jumping from a percentage to an amount, and we should start our analysis there.

Here, the Manager brings up the percentage of each computer's sale price is profit, and low-end models have a profit margin almost double that of the high-end models. From this, the argument concludes that profits will be maximized by switching to just selling them, since they can't stock unlimited models on the floor.

Is that conclusion about an amount? It sure is—maximizing profits means making as much money as possible, not having the highest percentage of profits. So this argument does commit a jump between percentage and amount. After all, it's possible to make $25 off of each of a ton of $100 computers, while selling fewer $2000 models at $260 profit/apiece and making more money overall.

But, again, don't do the math! As long as the argument jumps from a percentage to an amount, you've identified your flaw.

Answer Explanation:
This answer highlights that the premises of the argument never address the total money earned per computer. If the total amount earned is much higher, even if the percentage is lower, those high-end models could turn the larger profit.

Key Takeaway:
Don't do math on the LSAT. Know how the LSAT uses math to create flawed arguments, and know the elements that go into those flaws. That way, you can identify the relevant flaws—e.g., the percent and amount flaw here—without needing to walk through any math.

Incorrect. The argument discusses the profit made per sale, so it's not assuming equivalent sales. This answer would be correct if the argument used a premise about the total amount made on one category of computer to make a recommendation to shift to that model, failing to take into account that more of them may have been sold.

Incorrect. This answer choice is trying to get you to think that the store is leaving money on the table by selling only low-end models, since some people would "upgrade" to the more expensive models. However, the argument doesn't ignore that possibility, but rather thinks that they'd be better off not upgrading that computer for the customer since they'd make a lower percentage of profit off of it. That's bad reasoning, but it's reasoning considered by the Manager, so we can't say she ignores this possibility.

Incorrect. The argument assumes that maximizing profit is an important objective, but this answer goes too far in stating that the Manager assumes it's the only objective. Even if there is a secondary objective, maximizing profit could still be important enough to make decisions around. The conclusion is also a bit qualified by the statement about profit, establishing it as being key to the recommendation in the conclusion.

Incorrect. If anything, the argument is assuming that future sales will not be the same as past sales—they'll be higher when there are more of them on display and for sale.