PrepTest 119, Section 3, Question 22
Over the last 10 years, there has been(44 more words not shown)
Which one of the following,(7 more words not shown)
- AThe number of(16 more words not shown)
- BThe birth rate(10 more words not shown)
- CThe total number(13 more words not shown)
- DThe number of(21 more words not shown)
- EThe average age(14 more words not shown)
Reading the argument
A higher average age doesn't necessarily mean more people over 65. What if younger people are leaving?
Imagine a town losing many of its young residents while its older population stays the same. The average age could rise without the number of older residents increasing. That's the gap between the evidence and the conclusion: an average describes the mix of ages, not how many people belong to a particular age group.
What we’re looking for
We need to strengthen the claim that the over-65 population increased. I'd look for something that challenges the idea that fewer young people explain the higher average. Information about overall population growth might help too. I'm not yet sure which route the choices will take. Let's see whether they address the age mix or just the number of residents.
Working the answers
- ACorrect
The number of residents under 18 increased. That works against the particular explanation we considered: the average rose simply because the region lost its young people. These additional young residents would ordinarily pull an average of 52 or 57 downward, so the rising average suggests a countervailing shift toward older ages.
This supports the author's interpretation; it doesn't prove it. The answer doesn't account for every change among adults or establish exactly how many people crossed the age-65 threshold. We need the strongest support offered, not a guarantee that every possible alternative has disappeared.
- B
A lower birth rate provides another way for the population's age mix to shift upward without requiring more people over 65. It therefore doesn't support the inference we need. Also, a birth rate isn't the same as the number of people moving away; we shouldn't turn this into evidence about migration.
- C
A falling total population is compatible with the younger-residents-leaving explanation. It doesn't identify which ages declined or establish that the over-65 count rose. A higher average in a smaller population still needn't mean more older people.
- D
This is tempting because more people moved in than moved out. But how old were they? The newcomers could be middle-aged rather than over 65. We also aren't given the births and deaths needed to settle the total population change. D doesn't address the age mix as directly as A does.
For example, an influx of people in their late fifties could push up an average near 52 without adding anyone over 65. Net immigration alone doesn't establish the particular increase the author claims.
- E
We care about change within this region over ten years. Being older on average than neighboring regions doesn't tell us whether this region gained older residents, lost younger residents, or changed in some other way. The comparison leaves the explanation for the local increase unsettled.
More Strengthen questions
Learn the LSAT our way
Our platform drills Strengthen questions at your level and adjusts as you improve.