Logical Reasoning · Necessary Assumption

PrepTest 153 · Section 2 · Question 4

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

Step 1 · Pre-Question Guidance · read this first

Question type

Necessary Assumption

The one idea it tests

The argument links 'needs less demanding effort' to 'good for people short on time'; it needs the hidden bridge that more demanding effort takes more time.

The basic logic

Look for a jump between two ideas that sound close but are different: one premise talks about how intense something must be, the conclusion talks about limited time. The assumption connects them. Pull the Plank: negate it and the argument falls.

Tiny words that decide it

“less”
“more apt”
“limited”

Playground logic

Priya's patty says volcano projects need less detailed decorating, and skimpy decorating looks sloppy. Her top bun says busy kids should pick volcanoes. The secret sauce: detailed decorating takes more time. Pull that plank and the plan collapses.

Step 2 · The kid story

The Science Fair Shortcut

The science fair is in three days and Owen has soccer every night. Priya gives advice. "Volcano projects need less detailed decorating than robot projects to look good. And a project that does not get the detail it needs looks sloppy. So for a kid with very little time, a volcano is less likely to look sloppy." Lulu writes it down, then taps her pencil. "But what if detailed decorating is quick? What if fancy robot stickers take two minutes?" Priya grins. "Then my advice falls apart. I am assuming that more detailed decorating eats up more time. Without that, a busy kid could make a robot just fine."

Step 3 · Try the model question

Priya: Volcano projects need less detailed decorating than robot projects to look good. A project not decorated with the detail it needs is more likely to look sloppy. So for a kid with little time, a volcano project is less likely to look sloppy than a robot project.

Priya's argument depends on which assumption?

Step 4 · The courtroom tale

The Case of the Garden Hedges

A homeowners' club told its busy members: "Boxwood hedges need less careful trimming than rose hedges to look neat, and a hedge without the care it needs looks messy. So busy owners should plant boxwood." A rose seller, Ms. Dunn, objected in court. Mr. Whitfield, for the club, declared the advice airtight. Judge Abara frowned. "Counselor, the advice talks about careful trimming. The members are short on time. Does careful trimming take longer?" Mr. Whitfield blinked. "I assumed so." "You did," said the judge. "And if careful trimming took no extra time, your busy members could keep roses neat. Your advice rests on that link."

Step 5 · Work the real question

Open PrepTest 153, Section 2, Question 4 in your official copy from LSAC (for example in LawHub) and read it there.

Your answer

How to apply it

Find the two ideas the argument blends: the premise speaks about one quality of effort, the conclusion speaks about having little time. State the bridge in your own words before reading the choices. Then Pull the Plank on each candidate: negate it and see whether the conclusion still stands. The right answer, once negated, cuts the link between the premise's quality and the conclusion's time limit. Drop choices that go too far or bring in new topics.