Critical Reasoning

Investigators concluded that human failure was not responsible for the fatal airplane crash last August, and since that time new and more stringent rules for identifying and reporting mechanical problems have been in effect. That accounts for the fact that reports of airplane mechanical problems have increased in frequency by 50 percent since last August.

Which one of the following is an assumption underlying the argument in the passage?

(A) Airplane travel is still relatively safe, despite the increase in reported mechanical problems.

(B) Mechanical problems in airplanes have increased dramatically since last August.

(C) Mechanical problems in airplanes have not increased by 50 percent since last August.

(D) Airlines are less reluctant to report mechanical problems than they previously were.

(E) Mechanical problems in airplanes have become easier to detect since last August.
OA after discussions

IMO D..Please post OA

C for me

A. out of scope

B. weakens. gives an alternative cause

C. negate. leads us to B and weakens. if mechanical problems have gone up by 50%, then it weakens the conclusion that stringent rules have led to 50% increase in reports of mechanical problems.

D. out of scope

E. weakens. gives an alternative cause

(A) Airplane travel is still relatively safe, despite the increase in reported mechanical problems. – the fact that airplane is still safe is out of scope, it doesn’t explain the increased number of reports of mechanical problems

(B) Mechanical problems in airplanes have increased dramatically since last August. – according to the argument, the number of reports has increased dramatically, but not the actual mechanical problems (reports don’t mean actual mechanical problems as reports can be false)

(C) Mechanical problems in airplanes have not increased by 50 percent since last August – CORRECT as the conclusion is the reports were increased by 50% which means already existing problems were reported rather than new problems.

(D) Airlines are less reluctant to report mechanical problems than they previously were. – how reluctant are airlines to report mechanical problems is not applicable to our case

(E) Mechanical problems in airplanes have become easier to detect since last August. – the fact that mechanical problems have become easier to detect is out of scope [/b]

one more for C

If problems have not increased by 50 % then only the new laws were effective in bringing problems which were not reported earlier...

if problems have increased by 50 % then new law doesn't make sense as those problem would have been reported even in the absence of any law...

i would say (E)

I still feel E should be the answer