Critical Reasoning

OA is B.

This is an LSAT question. It is taken from the October 1993 LSAT test, the first logical reasoning section, question number 17.

Scorpionz has put out a nice explanation here. Please read that post above.

Here is my explanation - by the way, I teach this question when I teach the LSAT so I have taught this one a dozen times at least.


First of all, for an easy way to eliminate several choices, we see that there is no comparison between stainless steel and nylon. The comparisons are between the energy required to produce certain instruments and the energy required to sterilize those same instruments. So the comparison is energy and it is only stainless steel to stainless steel and nylon to nylon.

This fact alone eliminates choices A C and D all three of which make the comparison of stainless to nylon.

Choice E can be eliminated because we are told only of energy use and not of "cost."

So we can see that B is the only possibility.

Choice B must be false because while the sterilizations require 3.4 times the energy, remember that this is for 50 sterilizations. So you would see that if it takes 100 units of energy to produce a set that means 340 units for sterilization. But that is for 50 sterilizations, so divide that by 50. So it is like 7 units of energy to sterilize each time compared to 100 units to produce the set. So B must be false.

By the way, this was a question 17 on the LSAT that is the area of each section with the toughest questions. So this - although straight forward when explained - a as tough as anything on the GMAT.