Logical Reasoning · Inference

PrepTest 128 · Section 3 · 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

Inference

The one idea it tests

Chain two 'only' facts. If a certain place gets its contents from just one source, and a certain item is found only in that place, then only that source can supply the item.

The basic logic

Lunchbox Rule: use only what is packed. Link 'X shows up only in place P' with 'place P is filled only by source S'. The safe answer says only S can provide X. Watch for answers that flip 'only' into 'all' or add claims about importance.

Tiny words that decide it

“only”
“exclusively”
“equally”

Playground logic

At the picnic, both families bring main dishes, but only Aunt Rosa's family brings desserts. Brownies are only ever a dessert. Put the two together: only Aunt Rosa's family can bring brownies.

Step 2 · The kid story

Who Brings the Brownies?

Every summer, Tommy's family and Aunt Rosa's family hold a giant picnic. The rule is old and strict. Both families bring the same number of main dishes. But desserts come only from Aunt Rosa's family. Tommy complains. "Why can't we bring dessert?" Grandpa shrugs. "Rule's a rule." Lulu writes on her clipboard. "Here's another fact. At this picnic, brownies are only ever served as dessert." Tommy's eyes go wide. "So if I want brownies, they have to come from Aunt Rosa's family." Marcus leaps in. "So Aunt Rosa's family always brings brownies!" Priya shakes her head. "Nope. They might bring pie. We only know that if brownies show up, they came from her side." Biscuit hopes for brownies anyway.

Step 3 · Try the model question

At the family picnic, both families bring the same number of main dishes. Desserts, however, come only from Aunt Rosa's family. At this picnic, brownies are only ever served as dessert.

Which one of the following can be properly concluded from these statements?

Step 4 · The courtroom tale

The Case of the Golden Bolts

A bicycle factory is on trial for a missing shipment of golden bolts. Mr. Whitfield explains the rules to the jury. "Two warehouses supply this factory. Both send wheels. But seats come only from the North Warehouse." He holds up a shiny bolt. "And golden bolts are used only on seats." Judge Wanda Cho leans in. "So golden bolts can arrive only from the North Warehouse." "Correct, Your Honor." The South Warehouse manager breathes out in relief. A juror asks, "Does North always send golden bolts?" Mr. Whitfield smiles. "The rules don't say that. They only say where golden bolts could come from." The jury nods.

Step 5 · Work the real question

Open PrepTest 128, Section 3, Question 13 in your official copy from LSAC (for example in LawHub) and read it there.

Your answer

How to apply it

Mark every 'only' and 'exclusively' in the passage. Find the item that lives in just one place, and the source that alone fills that place. Chain them. The supported answer says only that source can supply the item. Reject answers that turn 'only' into 'all' or 'always', compare importance, or predict new discoveries. Use the Spoiler Test: if it might be false, cross it out.