Bunuel wrote:
During the period in which there are no competitive races, two runners--Runners A and Runners B--take part in an experiment measuring their VO2 max, the volume of oxygen an athlete can use. During these sessions, the runners engaged in moderate aerobic activity, or a sustained heart rate between 146-154 beats per minute. At the end of the sessions, Runner A had a greater VO2 max than Runner B. Therefore, once the two runners begin identical intensive training--sessions involving over 168 beats per minute-- for the race season, Runner A will continue to have the greater VO2 max, assuming that neither become injured and that both train with similar intensity.
Which of the following is an assumption upon which the argument rests?
(A) Runner A and Runner B had similar VO2 maxes uponentering the study.
(B) Regarding their VO2 maxes, runners respond equally to intensive training.
(C) Intensive training involves sessions in which athletes maintain a heartbeat over 168 beats per minute.
(D) The amount one trains does not influence one’s VO2 max.
(E) During the experiment, Runner A did not always have the greater VO2 max than Runner B.
OFFICIAL EXPLANATION
Premise #1 – A > B (VO2 max) after moderate aerobic activity.
Conclusion: Runners will begin identical intensive training, A will continue to have greater V02 max.
Assumption: The effects of intensive training on the two runners are equivalent to the effects of moderate aerobic training.
(A) directly contradicts what is stated in the passage: Runner A had a greater VO2 max than B.
(B), if it is not true, represents a possible flaw in the conclusion. Say Runner A responds to intensive training differently than Runner B, then it is possible that Runner A will NOT have a greater VO2 max than runner B.
(C) just quantifies what is meant by intensive training. It doesn’t relate to the argument as a whole.
(D) is tempting but remember the argument says that “both will train with similar intensity” and will engage in “identical intensive training”.
(E) is somewhat of a weakener. That is, it points to the possibility that the VO2 max fluctuated throughout the experiment and Runner A just happened to have the higher VO2 max at the very end of training.
An assumption, however, doesn’t weaken the conclusion, but is the very foundation upon which the conclusion rests. That’s why we negate assumptions. In other words, if I pull the foundation out from under the house and that house still stands, then the original assumption was not one that supported the conclusion. However, if I negate the assumption and the conclusion then totally falls apart, we know the original assumption is one upon which the argument depends.
By negating (E), “Runner A always had the greater VO2 max…”, we actually strengthen the conclusion. Therefore, (E) is not the answer.
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