Logical Reasoning · Must Be True

PrepTest 142 · Section 4 · 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

Must Be True

The one idea it tests

Chain the conditional rules together and follow only where they lead.

The basic logic

Write each rule as an arrow: everyone gets the baseline; some members qualify for extras; qualified members who ask always get the extra. Link the arrows. The answer must follow from a full chain, starting where the rules start. Watch for reversed arrows and for claims about members who never asked.

Tiny words that decide it

“at least”
“all”
“if”
“unless”

Playground logic

Every kid gets one or more library visits every week. Qualified kids who ask for an extra visit get it right away. So a qualified kid who asks ends up with more than one visit that week. That is the whole lunchbox, and nothing more.

Step 2 · The kid story

The Library Pass Rules

Ms. Rivera posted the new library rules. 'Every student gets one or more library visits every week. Students who need more time, for example because of a big research project, qualify for an extra pass. Any qualified student who asks for an extra pass gets one right away.' Marcus read it twice. 'So everyone with a big project gets two visits!' Lulu tapped her clipboard. 'Only if they ask. The rule says qualified kids who ask get it.' Kevin raised his hand. 'I asked, but I'm not doing a project. I just like the joke books.' 'Then the rule does not promise you anything,' said Lulu. Priya summed it up. 'Here is what we know for sure: a qualified kid who asks gets more than one visit that week.'

Step 3 · Try the model question

Every student gets one or more library visits every week. Students who need more time qualify for an extra pass. Any qualified student who asks for an extra pass receives one right away.

If the rules above are all true, which one of the following must also be true?

Step 4 · The courtroom tale

The Extra Snack Rule

At a fictional summer camp hearing, the camp rule read: 'Every camper gets at least one snack a day. Campers who hike the long trail qualify for an extra snack. Any qualifying camper who asks gets an extra snack right away.' A camper named Jo sued, saying the camp promised her two snacks. Mr. Whitfield asked, 'Did Jo hike the long trail?' 'Yes.' 'Did she ask?' Silence. 'No.' 'Your Honor,' said Mr. Whitfield, 'the rule only guarantees more than one snack to a qualifying camper who asks. Jo qualified, but she never asked. The chain stops halfway.' The judge agreed. 'Next time, Jo, ask for the granola bar.'

Step 5 · Work the real question

Open PrepTest 142, Section 4, Question 13 in your official copy from LSAC (for example in LawHub) and read it there.

Your answer

How to apply it

Turn each rule into an arrow and note the baseline that applies to everyone. Look for the answer that starts at the front of a chain and rides every arrow to the end, combining the baseline with any guaranteed extra. Be suspicious of answers that run an arrow backwards, that drop a required condition (such as asking), or that say something about cases the rules leave open.