Logical Reasoning · Sufficient Assumption
PrepTest 125 · Section 2 · Question 13
Phase 1 (your first ~400 questions): read the guidance, then answer. No clock.
Step 1 · Pre-Question Guidance · read this first
- “neither”
- “nor”
- “eventually”
- “do not”
Playground logic
At the lemonade stand, Nadia says stands that don't draw kids close up shop. Then she concludes stands that are neither the sweetest nor the cheapest will close. The magic key: a stand that is neither sweetest nor cheapest won't draw kids.
Step 2 · The kid story
The Lemonade Stand Shake-Out
Five lemonade stands lined Maple Street on Saturday. Nadia, notebook out, made a rule: "Kids want the sweetest lemonade for the fewest quarters. Any stand kids don't come to closes by lunch." Then she announced: "So any stand that's neither the sweetest nor the cheapest will close by lunch." Owen frowned. "Wait. What if a stand has a cute dog? Biscuit could pull in customers." Priya nodded. "Nadia needs one more piece: that a stand which is neither sweetest nor cheapest won't bring kids over. Click that in, and her conclusion snaps shut." Tommy, at the stand with the worst lemonade, quietly hid his candy prices.
Step 3 · Try the model question
Nadia: Stands that fail to draw kids close by lunch. So any stand that is neither the sweetest nor the cheapest will close by lunch.
Which assumption, added to Nadia's premise, would guarantee her conclusion?
Step 4 · The courtroom tale
The Bakery Bet
A bakery owner sued a rival who predicted her shop would fail. The rival's expert testified: "Shops that don't win customers go under. Her shop has neither the best bread nor the lowest prices. So it will go under." Mr. Whitfield tugged his suspenders. "Your Honor, the expert skipped a step. He needs to show that a shop with neither the best bread nor the lowest prices fails to win customers. Without that, the logic has a gap." The judge agreed. "Supply that link and the argument is airtight. Without it, it is a guess." The bakery owner handed out muffins. The court ruled them evidence of customer appeal.
Step 5 · Work the real question
Open PrepTest 125, Section 2, Question 13 in your official copy from LSAC (for example in LawHub) and read it there.
Your answer
How to apply it
Write the premise as a conditional and the conclusion as a conditional. Spot the term in the conclusion's 'if' part that appears in no premise. Find the answer that says that term guarantees the premise's 'if' part. Test it by plugging it in: does the conclusion now have to follow? Avoid choices that reverse the direction or talk about the opposite group.