PrepTest 109, Section 3, Question 5
The radiation absorbed by someone during an ordinary(45 more words not shown)
A flaw in the argument(6 more words not shown)
- Athere may be(21 more words not shown)
- Breceiving a dental(10 more words not shown)
- Cexposure to X-rays(9 more words not shown)
- Dthe longer and(20 more words not shown)
- Eflying at high(10 more words not shown)
Reading the argument
A flight crew member doesn't take just one flight.
Let's accept the comparison we're given: the radiation from an ordinary flight is no more dangerous than the radiation from an ordinary dental X-ray. The next premise says the dental X-ray does negligible harm. That gives us a reassuring comparison for one flight.
But the conclusion concerns the radiation absorbed by people whose work involves repeated flights. Imagine someone getting an occasional dental X-ray while a flight attendant flies again and again throughout the year. Even if each flight contributes only a small amount of harm, repeated exposure could add up. The one-occasion comparison doesn't settle the effect of the whole pattern.
What we’re looking for
That's what I'd expect the flaw answer to identify: the argument leaves out how often the exposure happens. We aren't trying to show that every flight is dangerous or that flying is unsafe in every respect. We need to explain why a negligible risk on one occasion doesn't establish negligible harm for the crew over time.
Working the answers
- A
Other kinds of dangerous radiation don't address this inference. The conclusion concerns the radiation these crews absorb during commercial flights. Naming additional forms of radiation would matter only if we were told that the crews receive relevant exposure to them. A doesn't supply that connection.
- B
A dental X-ray might help identify another health problem. That benefit doesn't determine how much harm the radiation itself does. The argument compares harm from radiation, not the overall balance of every benefit and risk associated with dentistry and flying. B doesn't address the crew's repeated exposure.
- C
We are given a comparison with an ordinary dental X-ray. The danger of higher-intensity X-rays doesn't establish a problem with that comparison, because nothing says the flight exposure is to those higher-intensity X-rays. The issue is the repeated ordinary exposure the conclusion overlooks.
- DCorrect
The amount absorbed and the harm can increase with longer and more frequent exposure. That makes the crew's repeated flights matter. A small exposure on each occasion can accumulate into more than negligible harm over time.
The original comparison already concerns an ordinary flight, so we shouldn't simply ignore that premise because a flight lasts longer than an X-ray. The decisive gap is the move from that single-flight comparison to the exposure accumulated by the crew across many flights. D directly identifies why that move needs support.
- E
Other risks of high-altitude flying don't show that its radiation is harmful. Even if flying had a separate risk unrelated to radiation, the conclusion about radiation could still be true. Keep the objection tied to the particular harm the author dismisses.
More Flaw questions
Learn the LSAT our way
Our platform drills Flaw questions at your level and adjusts as you improve.