Critical Reasoning

In the nation of Partoria,large trucks currently have much higher rate of traffic accidents per mile driven than other vehicles do.However, the very largest trucks- those with three trailers- had less than a third of the accident rate of single and double trailer trucks.clearly, therefore,one way for Partoria to reduce the number of traffic accidents would be to require shippers to increase their use of triple trailer trucks.

Which of the following, if true, most seriously weakens the argument?

a.Partorian trucking companies currently use triple trailer trucks only for long trips using highways,which is the safest kind of trip for large trucks.

b.No matter what changes Partoria makes in the regulation of trucking, it will have to keep some smaller roads off-limits to all large trucks.

c.Increased use of triple trailer trucks would mean that large trucks would account for smaller proportion of all miles driven on Partoria's road than they currently do.

d.In Partoria, the safety record of the trucking industry as a whole has improved slightly over the past ten years.

e.The volume of truck traffic in Partoria's highways could be reduced by encouraging shippers to use rail transport whenever possible.

A

Hi Experts,

I am specifically interested in discussing option C and D. Please suggest if my reasoning is correct or not.

c.Increased use of triple trailer trucks would mean that large trucks would account for smaller proportion of all miles driven on Partoria's road than they currently do. - I think this is opposite i.e a strenghthener since it strengthens the conclusion that increase in large trucks will lead to lesser accidents.

d.In Partoria, the safety record of the trucking industry as a whole has improved slightly over the past ten years. - I think this is Irrelevant. Even if the entire trucking industry has improved doesn't mean that the standards can't be improved further and hence the plan advised may be effective. Whereas this option has no effect on the conclusion.

Hi nishatfarhat87,

Let's start with the premises and the conclusions:

Premise 1: Large trucks = higher rate of accidents per mile driven than any other vehicle. Essentially, if cumulatively large trucks have driven 100 miles, there could have been x number of accidents which is the highest number for that statistic
Premise 2: Largest trucks ie trucks with three trailers had less than 1/3 of the accident rate than single and double trailer trucks. So, if for the very large trucks the rate of number of accidents was z per 100 miles, it was atleast 3z for single trailer and double trailer trucks

Conclusion: One way to reduce number of traffic accidents for country P is to have shippers increase use of triple trailer trucks.

Let's start looking at the options:

A. This option directly attacks the 2nd premise. The premise which showcases the safety of triple trailer trucks clearly has a strong reason for that safety. This implies that if their use is increased to beyond the highways (which is the safer stretch to travel for a truck) then they might not remain as safe. CORRECT

B. The stimulus in no way discussed the possibility of extending smaller off-limit roads to the large trucks. Irrelevant. INCORRECT.

C. The reasoning behind the statement could be that if the shippers start using very large trucks, they will need lesser trucks leading to lesser miles of the traffic in country P. You are right, it does end up strengthening the conclusion as it does nothing to attack the safety of the triple trailer truck and ends up giving another benefit of using the very large trucks. INCORRECT.

D. As pointed out by you, it is indeed irrelevant. The fact remains that the trucks' record still remains the highest contributor to the no. of accidents per mile travelled and the fact that this rate is an improvement over the previous year does nothing to strengthen or weaken the argument. INCORRECT

E. While this is another option to reduce the rate of number of accidents per mile travelled by reducing truck traffic altogether, it doesn't talk about the conclusion mentioned in the stimulus. What it does is to give an alternate option. INCORRECT

So, the answer is A.