Logical Reasoning · Weaken

PrepTest 151 · Section 2 · Question 9

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

Step 1 · Pre-Question Guidance · read this first

Question type

Weaken

The one idea it tests

An average per person dropped, and the arguer blames unwillingness; but adding more people to share the work also lowers the average.

The basic logic

The evidence is a per-person rate. The conclusion is a cause (people pulled back). Look for another explanation of the drop, especially a change in how many people are counted in the bottom of the fraction.

Tiny words that decide it

“per”
“average”
“must have”

Playground logic

Marcus sees fewer sessions per buddy and says kids must be avoiding them. The patty is a per-buddy number. Pop it by showing the school added lots more buddies, so each one simply had fewer sessions.

Step 2 · The kid story

The Reading Buddy Mystery

Last spring the school poured money into the reading-buddy program. Two years ago, each buddy read with about 30 kids a month. Last month, only 20. Marcus slammed his notebook. "Case solved! All the extra fuss annoyed the kids. They're hiding from the buddies!" Priya sipped her juice box. "Or the school used that money to sign up twice as many buddies. Same number of kids, more buddies. Each buddy gets fewer kids." Marcus paused. "So nobody's hiding?" Lulu tapped the clipboard. "The total could even go up. You only looked at the number per buddy." Biscuit, under the desk, was the only one hiding, from a bath.

Step 3 · Try the model question

The school spent more on its reading-buddy program last year. Two years ago, each buddy averaged 30 reading sessions a month; last year the average fell to 20. So the extra spending must have backfired, making kids less willing to meet with buddies.

Which choice, if true, does the most to undercut the argument?

Step 4 · The courtroom tale

The Ice Cream Truck Hearing

A fictional town sued a frozen treat company. "Two years ago, each truck sold 500 cones a week," said the town's lawyer. "Now each sells 350. The company's loud new jingle must have scared customers away!" Mr. Whitfield stood and snapped his suspenders. "Your Honor, the company also bought twice as many trucks. More trucks, same hungry kids. Each truck sells fewer cones, but the town eats more ice cream than ever." The judge checked the receipts. "The per-truck number fell because the trucks multiplied. The jingle is innocent." A child in the gallery whispered, "Can we hear the jingle?"

Step 5 · Work the real question

Open PrepTest 151, Section 2, Question 9 in your official copy from LSAC (for example in LawHub) and read it there.

Your answer

How to apply it

Identify the per-person figure in the evidence and the cause the arguer gives for its change. Ask what else could make that average fall: often, a larger group sharing the same work. Pick the choice that offers that alternative explanation, leaving the claimed cause unneeded. Ignore choices that only describe what happens during contacts, or other spending that the argument never relied on.