On the GMAT when you are faced with Critical Reasoning “explain” questions, your task is to identify the two pieces of information that appear to contradict and look for the answer choice that explains why they do not. For practice, try the problem below.
A series of experiments was conducted in which rats of various ages were placed in a series of mazes and timed to see how long it took them to find their way out. In the first set of runs, the younger rats made their way out of the mazes an average of 30 percent faster than the older rats. Three days later, however, when the same rats were placed in the same mazes, the older rats were faster by nearly 40 percent.
Which of the following hypothesis best accounts for the findings of the experiments?
(A) A rat's sense of smell becomes less acute as it gets older.
(B) The older rats had been used in earlier experiments.
(C) Older rats have better-developed sensory memory, which allows them to "remember" the mazes three days later.
(D) Younger rats become frustrated when faced with repeated dead ends in a maze, while older rats do not.
(E) Older rats tire more easily than younger rats.
Remember, “explain” questions will not have a conclusion - instead start by identifying the two pieces evidence. In our problem, the first piece of evidence is that in the first experiment the younger rats found their way out of the maze more quickly than the older rats. The second piece of evidence that appears to contradict the first is that the older rats finished the maze more quickly in the second experiment.
Now we need to assess the answer choices one at a time, until we find a choice that explains how both pieces of evidence can be true. On many types of Critical Reasoning Questions, you will be trying to predict an answer quickly so that you know what you are looking for. However, on “explain” questions, you will not easily be able to predict an answer choice since there are numerous possible explanations, so you must go immediately to the choices and start assessing each option and eliminating as you go.
Option (A) is out of scope - we are not concerned with the rats' sense of smell.
Option (B) is also out of scope - we have no interest in earlier experiments.
Option (C) tells us that the older rats have a better memory. If this is true, we would know why the older rats can complete the maze more quickly the second time through, even though they take longer to figure it out the first time. So, this IS one possible explanation to the unexplained scenario. As long as you are not short on time, you should still quickly read over the other choices, and here options (D) and (E) are also statements that are outside of the scope of this scenario, so (C) is correct.