Unplugged Practice Test: Logical Reasoning Set 3, Question 11 (Parallel Flaw)
Taking the test? Finish it first. This page shows the answer.
- Parallel Flaw questions ask you to match the argument's flawed structure.
- Predict what a correct answer needs to do before you read the choices.
- Every question on this test is original, written to the same logical skeletons as real questions, and Steve checked every one himself before release.
The question
Greenhouse tomatoes grown under supplemental lighting are less likely to split than tomatoes grown without it. So a tomato that has split was probably not grown under supplemental lighting.
11. The questionable reasoning above is most closely paralleled in which one of the following?
- (A)To qualify as a sonnet, a poem must have exactly 14 lines. So poems with about that many lines are not sonnets.
- (B)Roofs finished with reflective sealant are less likely to blister than roofs left bare. So a roof that has blistered was probably not finished with reflective sealant.
- (C)Every visitor who came in through the north gate was handed a wristband. So visitors who came in through the south gate were probably handed wristbands too.
- (D)Mice housed in cooled rooms live 15 percent longer than mice housed at room temperature. So most people could live longer by keeping their homes cooler.
- (E)Welders who finish the night certification course reach a certain standard of skill, so those welders owe that standard to the course alone.
BWhy (B) is correct
The tomato argument says lighting makes splitting less likely, then flips that into a claim that a split tomato was probably not grown under lighting. That reverses a less-likely relationship into a claim about which group a given case probably belongs to, when plenty of lighted tomatoes can still split. (B) does the identical flip: reflective sealant makes blistering less likely, so a blistered roof was probably not sealant-finished, even though sealant-finished roofs can still blister sometimes.
Why the other answers are wrong
AWhy (A) is wrong
(A) sets a strict line-count requirement for a category and reasons that anything near it fails that requirement, a definitional move, not a reversed likelihood.
CWhy (C) is wrong
(C) generalizes a fact true of every visitor at one gate to visitors at a different gate. That's a different mistake from flipping a probability.
DWhy (D) is wrong
(D) takes a result from mice and applies it wholesale to people, over-applying an animal study rather than reversing a likelihood.
EWhy (E) is wrong
(E) treats one course as the sole source of a skill. That's a sole-cause overreach.
Common questions
What type of question is this?
Parallel Flaw. Parallel Flaw questions ask you to match the argument's flawed structure.
How do I get better at Parallel Flaw questions?
Predict the answer before reading the choices. The free LSAT cheat sheet lists the wrong-answer patterns to watch for on every type.
