LSAT 110 | Section 3 | Logical Reasoning: Q21

LR Question 21 Explanation

QUESTION TEXT: Thirty years ago, the percentage of their income that…

QUESTION TYPE: Strengthen

CONCLUSION: Incomes must have risen faster than the price of food.

REASONING: People used to spend a larger percentage of their income on food.

ANALYSIS: This sounds like a good argument, but there are some nuances. For instance, people might be spending their food money differently. If you eat out less then you will spend less on food even though the price of food did not fall.

Also, the quantity of food might change. The right answer keeps things equal by telling us that food types and food quantity haven’t changed in 30 years.

___________

1. This isn’t determinative. If you eat the same amount of food as normal, but you eat it in a restaurant, then you will spend a lot more money. Maybe people just eat at restaurants less and spend less money for that reason.
2. We don’t know if healthier food costs more or less. This doesn’t help much. And if we’re eating less then maybe that is why we spend less on food. 
3. CORRECT. This holds everything equal. We purchase almost exactly what we did 30 years ago except we spend less. 
4. This doesn’t tell us how fast the price of food has risen. If anything it indicates that people might have had to cut back on food spending (and quantities) to afford everything else that was rising in price.
5. This indicates that single people may have changed their spending habits but prices probably stayed the same. Families are much more likely to be representative of food habits than single people since they count for more people.