#20 - In the past, when there was no highway speed limit,

[nutcracker]

Hello,

After reading through each answer choice, it became clear that (D) is the best one. However I want to make sure that my analysis of (A) through (C) is correct.

(A) looks like a strengthen answer to me, since it rules out the possibility that nobody was driving faster than the 90kph limit before it was instituted anyways.

(B) appears attractive initially but is probably out of scope, since it's talking about roads that are not highways, and the factors that can lead to accidents on those roads can be very different, making a comparison of the speed limits more or less meaningless.

(C) is saying that most drivers just ignore the speed limit, which I think also weakens the argument to some degree... Is there a better reason why it is not a good option other than that (D) is better? Thank you very much!

[Francis O'Rourke]

Your reasoning on answer choices (A) is sound.

Although answer choice (B) discusses roads in general, and the stimulus discusses highways, this answer choice is still relevant. After all, highways are a type of road! However, since we don't know how many accidents occurred on highways vs other roads, we can not conclude much from the information provided in this answer choice.

Answer choice (C) tells us that most people typically drive over the limit. This information does not effect the conclusion in the slightest. Since the conclusion only said that setting the legal speed limit caused the decline in accident rates, we should not assume that the speaker necessarily believes that everyone abided by that limit. For example, the speaker could assume that most people drive at 5 kph over the limit whether the posted speed limit is 80 kph, 90 kph, or 100 kph. What's important to focus on with answer choice (C) is that it attacked an argument that never appeared in the stimulus, but one which many test takers might mistakenly infer.

Answer choice (D) gives us a perfect alternate cause: perhaps it was the improvement in car handling over the past ten years that caused the decrease in accidents.

[brcibake]

I did not pick D because the stimulus did not mention dangerous situations. I felt E would be a better answer. Aren't E and D very similar anyways? Not sure what I missed here.
Thank you

[Adam Tyson]

Answer E has no impact on the accident rate, brcibake, but only on the amount of harm done to passengers who are involved in accidents. The accident rate could still have gone down as a result of the speed limit, even while the harm has been reduced further still by safety features like seatbelts. Since the stimulus has nothing to do with harm, answer E is irrelevant.

You're right that "dangerous situations" was not explicitly mentioned in the stimulus, but since this is a weaken question we should welcome new information into our analysis. If D is true, could the improved control be an alternate cause that explains fewer accidents? Dangerous conditions sound like they could lead to accidents. Wet roads, congested traffic conditions, sharp turns, limited visibility, etc. are all dangerous conditions that could increase accidents, and better control in those situations might help drivers avoid some of those accidents.

For certain question types (strengthen, weaken, justify, resolve the paradox, and to some extent assumption) actually require new info in the correct answer. While that new info would make the answer a loser if you were facing a Must Be True or Main Point question, among others, in those question types you should want that new info and embrace it when you find it. The question you must ask yourself is whether that new bit of info accomplishes the goal set out for you by the question stem. Does it make the conclusion more or less likely? Does it explain the odd situation? Does it prove the conclusion is true?

Don't fear new info! In the right context, it is exactly what you are looking for!

[deck1134]

Hi all,

Why is (B) wrong here? If 95% of all accidents were in places with a lower speed limit, it seems impossible that a 15% reduction could occur due to a different lowering. I've been running numbers for a while, and though we don't know the total, there really aren't any combinations that could leave a 15% reduction while 95% is taken.

Is the error with the 10 year window? Is that why (B) is wrong?

[student987]

Hello! I read Francis's explanation of why (B) is incorrect, but I am still a bit confused. Can someone explain a bit more in detail why (B) is wrong? Is it because "accidents on roads with a speed limit of under 80kph" (B) are not the same as the highway accidents, where, according to the stimulus, the speed limit is 90kph? Thank you!

[Brich]

I just did this practice test. I narrowed it down to B and D and picked D solely based on on the fact that B mentions roads rather than highways. All other answers mention highways and the question never mentions roads. If B said highways instead of roads, I would have picked that one. The fact that 95% of accidents happen on other roads has little relevance to how many happen on highways and a corresponding reduction in highway accidents, ie if 5% of accidents happen on highways, a 15% reduction is only dealing with that 5% and the other 95% are irrelevant.

[James Finch]

Highways are a sub-group of roads. The stimulus deals only with highways and why the accident rate has decreased on them, not roads in general nor what proportion of overall accidents on roads that highway accidents represent. So answer choice (B) can be eliminated as out-of-scope, since it doesn't show us the effect without the cause for highways, only roads in general (and we can infer, roads that aren't highways, as highways never had speed limits that low).

Instead, answer choice (D) gives us a much clearer alternate cause that would apply to highways: better ability to maintain control of a car. So this is the correct answer.

Hope this helps!

[jwheeler]

I also thought B was a convincing answer on the first go. My thought now upon review is as follows:
- Let's say that peak was 100 accidents in the year a decade ago (we'll say 2008 for ease)
- Ok, so the years after speed limit introduction, we'll say that there were no more than 85 accidents
- So if according to B there were 95% of wrecks happening on roads with speed limits <80kph, that would be 2000 wrecks at least in total, 100 of which were on highways, so 1900 were happening on other roads. That wouldn't account for the decrease in highway wrecks.

The numbers on this one seemed tricky to me (and I doubt you'd have time to do this hypothetical on the real test, but familiarizing yourself with the reasoning/concept now might pay off on a future question- that's what I'm banking on!). Hopefully this can help someone else who knew D was a better choice but was having trouble writing off B.

[Malila Robinson]

Hi jwheeler,
To expand a bit on the answers provided earlier, with Answer B what you need to focus on is the fact that it expands the discussion to all automobile accidents, whereas the stimulus was only talking about highway accidents. It could be that the vast majority of car accidents occurred on roads that are not highways. Because of this unknown we wouldn't know how to relate the cited 95% to the information in the stimulus. It might weaken in the way you described it, but it also might not weaken if the cited 95% didn't have much/any crossover with highway accidents.
Hope that helps!
Malila