Logical Reasoning · Method of Argument
PrepTest 101 · Section 2 · Question 3
Phase 1 (your first ~400 questions): read the guidance, then answer. No clock.
Step 1 · Pre-Question Guidance · read this first
- “one of”
- “nor”
- “therefore”
- “probably”
Playground logic
Lulu starts with three suspects. She crosses off the cat and the dog, each for its own reason. The one left, Tommy, is her conclusion: that is ruling out the rivals.
Step 2 · The kid story
The Cookie Crumb Trail
Somebody ate the last chocolate cookie, and Lulu was on the case. 'Only three suspects were home,' she said, holding up her clipboard. 'Tommy, Biscuit, and Mr. Whiskers.' She crossed out the first name. 'Mr. Whiskers was shut in the bathroom all afternoon. Grandpa let him out at dinner.' She crossed out the second. 'Biscuit is too short to reach the counter, even on his tiptoes, and the stool was still in the closet.' She looked up. 'So it was probably Tommy.' Tommy wiped crumbs off his shirt very slowly. 'Probably is a strong word,' he said. Priya, sipping her juice box, said, 'Lulu didn't catch you eating it. She just ruled out everyone else.' Biscuit wagged his tail, glad to be cleared.
Step 3 · Try the model question
Only Tommy, Biscuit, or Mr. Whiskers could have eaten the cookie. Mr. Whiskers was locked in the bathroom, and Biscuit cannot reach the counter. So Tommy probably ate the cookie.
Lulu reaches her conclusion by
Step 4 · The courtroom tale
Three Doors to the Vault
Mr. Whitfield drew three doors on the whiteboard. 'The thief entered the vault room by one of these: the front door, the window, or the air vent.' He put an X on the window. 'The window is painted shut, and the paint was not cracked.' He put an X on the air vent. 'The vent is too narrow for a person; the building inspector measured it.' He tapped the last door. 'That leaves the front door, Your Honor, and only two employees had its key.' The judge leaned in. 'You did not show us a video of anyone at the front door.' 'No, Your Honor. I showed you the only door still open after the others closed.'
Step 5 · Work the real question
Open PrepTest 101, Section 2, Question 3 in your official copy from LSAC (for example in LawHub) and read it there.
Your answer
How to apply it
Read for the skeleton, not the science. Look for an early sentence that sets up a short menu of possibilities. Then track each later sentence: does it cross one option off, and with what reason? Find the top bun and check that it names the last option standing. Pre-phrase the method as 'list the options, rule out the rest, keep the survivor.' Eliminate descriptions of moves the argument never makes (Phantom Pieces) and ones that borrow the right mood but the wrong action (Matching Costumes).