Logical reasoning PrepTest 110 · Section 3 · Question 21

Incorrect. First, this answer is about the amount of food per capita, not per single person, so the information here might not apply to that specific subgroup. Second, even if single people are eating the same amount of food, it might be all ramen and potatoes.

Incorrect. This answer brings up differences in the diets of single people today vs. 30 years ago, so these differences might explain the different percentage spent on food—not a slow growth rate in those costs. As such, this answer weakens the argument.

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Strengthen

Stimulus Summary:
30 years ago vs. today:
Single people spent 2x the percentage of their income on food as today
Over past 30 years — Incomes have gone up
Conclusion — Incomes have gone up faster than the cost of food

Answer Anticipation:
This argument compares the percentage of income spent on food today and 30 years ago for single people in order to draw a conclusion about the rate of increase in the cost of food and incomes.

We do learn that income has gone up, but the percentage of single person's income spent on food has gone down. In order to use that information to draw the conclusion, we'd need to know that the other factors that go into this determination stayed the same. If, for instance, single people are eating less, or they're buying lower—quality/cheaper food, then the decrease in percentage spent on food might be explained by that instead of a slower rate of growth in the cost of food.

Let's look for answers that establish a similarity in these other factors.

Answer Explanation:
This answer speaks specifically about single people, which lets us know that it applies to the stimulus (compare this to (A)). And it establishes that, as far as food is concerned, all other things are equal—the amount and type of food being eaten is the same. Since that's an apples—to—apples comparison (pun intended!), it strengthens the argument that the price of food must have gone up slower than incomes over the past 30 years to account for the lower percentage of income spent on it.

Key Takeaway:
Arguments that talk about the past and present are usually comparing something between the two times. As such, you should focus on what's similar, what's different, and what's the same—and if you're looking for an answer that brings up a similarity or difference between the time periods.

Incorrect. The comparison that matters is between income and the price of food—other increasing costs are out of scope.

Incorrect. The argument and conclusion are limited to discussing the spending habits of single people so families are out of scope.