***
Here's a Logical Reasoning question from the June 2005 exam.
Since the argument's short and straightforward, there's no need to make any symbols. The argument is that there must have been an increase in people over age 65 because the average age has increased significantly.
We can't pre-phrase here because several things might strengthen this argument. Let's look at the choices:
A) Correct. This makes us think that the rise in average age is due to an increase in older (> 65) people. With the average age increasing and the number of young people increasing as well, it's likely that you'll need more outliers (people > 65) to make up for the young people and increase the average age to 57 from 52. This doesn't have to be true - maybe there are just more people aged 57-64. However, the question only asks what would strengthen the argument, not what must be true. If true, this choice strengthens the argument.
B) The opposite of what we want. It suggests the increase in average age was due to there being fewer young people rather than there being more older (> 65) people. Lower birth rates in the last decade mean fewer very young (< style="font-weight: bold;">scope. This has no bearing on the argument, so it doesn't strengthen or weaken it. If there are fewer people around, this doesn't suggest the increase in average age is due to more > 65 people, nor does it suggest it's due to anything else. Aggregate population doesn't tell us anything about that rise in average age.
D) Wrong for the same reason as C. Population size, inflows/outflows, etc. have no bearing on this because the argument's about age.
E) Out of scope. This argument's talking about average age in this area going up, not its average age relative to that of other areas.
Remember:
Use scope and opposite as concepts to help you eliminate answers. A choice can't strengthen an argument if it's irrelevant. If the choice makes the argument appear less likely to be correct, it's incorrect also.
Good job using the comment feature to ask questions. Keep 'em coming!
I see in some previous post about the chain or reasoning diagram. Could some one please point out how and when it shouldbe used? It seems very useful and with practice, one should be able to do it mentally.
ReplyDeleteOther strategies and techniques and also greatly appreciated!
MORE QUESTIONS... pleeeeeeeeeeeeeeeease! :)
ReplyDeleteSorry to say ME, but Your reasoning doesn’t make much sense to me. I just don't see how an increase of young people (under 18) could have as a consequence the increase in the average age and therefore strengthen the argument.
ReplyDeleteYou are assuming that a rise in young people plus a rise in average age means more old people to balance the result, hence strengthening the argument. But this asumption is wrong, ‘cause it relies in another assumption that is actually the conclution draw by the argument, that over the last 10 years the number of people over 65 has increased. With the statement of option A) alone you can’t strenthen the argument.
This becomes evident if you do some simple exercises with a very small population sample; the trend shows that an increase in young people lowers the average age, whilst contradicting the argument.
On the other hand, a significant decrease in the birth rate, like stated in option B), significantly increases the average age of the population, and we can validly assume that the number of people over 65 has increased during the last 10 years, so this should be the answer.
By the way, your blog is great. I'll send some Q during this w/e.
Bye
RB (rboza@mixmail.com)
no, you're wrong. Its given that the average age has increased. It asks what together with that fact would best suggest that there has been a dramatic increase in those over 65. A decrease in the birth rate would lower the average age by itself, so there would be no reason to believe that its accompanied by a dramatic rise in those over 65.
ReplyDeleteOOOH I am so confsed. If you add more young people to a population then average age will decrease. Answer "A" seems to disprove the argument, not support it.
ReplyDeleteDear Anonymous
ReplyDeleteThat's exactly right, an increase in young people would mean a decrease in the average age ... therefore contradicting the argument.
To me the right answer is the fall in the birth rate.
Regards.
RB
Explanation makes perfect sense to me. "An increase in young people would mean a decrease in the average age ..." yes, UNLESS there has been an even greater increase in the number of old people (people over 65, even)...sound familiar? Oh yeah...that's the argument.
ReplyDelete