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Logical Reasoning · Parallel Reasoning

PrepTest 106 · Section 1 · Question 13

Phase 1 (your first ~400 questions): read the guidance, then answer. No clock.

Step 1 · Pre-Question Guidance · read this first

Question type
Parallel Reasoning
The one idea it tests
Match the skeleton: a condition means no problem, no problem means no fix, someone uses the fix, so they lack the condition.
The basic logic
X-Ray the stimulus into arrows: A leads to no problem; so A leads to not using the fix; this person uses the fix; so not A. It is a valid contrapositive move at the end. Find the choice with the same chain and the same kind of ending.
Tiny words that decide it
  • “hence”
  • “so”
  • “must not”

Playground logic

Kids who wash their hands before snack do not get sticky fingers, so they do not need wet wipes. Tommy uses a mountain of wet wipes, so Tommy must not wash his hands. That skeleton is the X-Ray to carry to the choices.

Step 2 · The kid story

The Wet Wipe Mountain

At snack time, Lulu noticed a mountain of used wet wipes next to Tommy. She started her X-Ray. "Rule one: kids who wash their hands before snack do not get sticky fingers. Rule two: so kids who wash first do not need wet wipes. Fact: Tommy used eleven wet wipes. So Tommy did not wash his hands." Tommy hid a gummy worm behind his back. "Fine. I skipped the sink." Priya nodded. "The bones of that argument are simple. Some habit means no mess. No mess means no cleanup tool. Someone grabbed the cleanup tool. So they skipped the habit." Lulu drew it as arrows: Wash, then no sticky, then no wipes. Wipes, so no wash. "Now any argument with the same bones is a twin," she said, "even if it is about bikes or socks."

Step 3 · Try the model question

Kids who wash their hands before snack do not get sticky fingers, so they do not use wet wipes. Tommy used a whole stack of wet wipes, so he must not have washed his hands.

Which argument has bones most like Lulu's argument?

Choices

Step 4 · The courtroom tale

The Mittens Defense

Mr. Whitfield faced the jury in a case about a missing snow shovel. "Folks who have heated driveways never get ice. So folks with heated driveways never buy ice melt. Mr. Grover bought six bags of ice melt this winter. So Mr. Grover does not have a heated driveway, and his brochure claiming one was false advertising for his house sale." The opposing lawyer, Ms. Lin, frowned but nodded. "The chain holds, Your Honor, if those rules are true." The judge wrote three arrows on a notepad. "Condition, no problem, no fix. Fix is present, so no condition. I have seen this shape before." Mr. Whitfield beamed. "Same bones as every good snack time argument."

Step 5 · Work the real question

Open PrepTest 106, Section 1, Question 13 in your official copy from LSAC (for example in LawHub) and read it there.

Your answer

How to apply it

X-Ray the stimulus into arrows before reading the choices: condition leads to no problem, which leads to no fix; the fix shows up; so the condition is absent. Note that the conclusion is a firm must, reached by the contrapositive. Check each choice for the same chain, same direction, and same strength. Cross off choices that reverse an arrow, compare things, give advice, or reach a prediction instead.