All of the cargo ships of the Blue

A free, expert breakdown of this official LSAT Logical Reasoning question.

TopicsMust be True

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Stimulus

All of the cargo ships of the Blue Star Line are over 100 meters long, and all of its passenger ships are under 100 meters long. Most of the ships of the Blue Star Line were built before 1980. All of the passenger and cargo ships of the Gold Star line were meters long. The S.S. Coral is a cargo ship that is currently docked at Port Tropica.

What this question is testing

Must be True

Your task

Break the argument into its conclusion and evidence, then do exactly what the question stem asks with that structure.

Common trap

Answers that sound relevant to the topic but don't connect to the argument's actual reasoning.

Winning move

Predict what a right answer must do, then test each choice against the conclusion-evidence gap.

Reading along? Open the full official question in LawHub — we show a fragment here and keep the reasoning in our own words.

The question

18.

If the statements above are true, which one of the following must be true on the

Answer choices

Correct80% picked this
The S.S. Coral was built after
Why this is right
Since it's docked at PT, it's gotta be Blue or Gold Star line and it's gotta be under 100m. Thus, of the two options (Blue Star cargo or Gold Star cargo) it could only be a Gold Star cargo ship. And since it's a Gold Star cargo ship, we know it was built after 1980.
Skill tested: Must be True · how this choice captures the argument's function is the move to repeat next time.
80%
Contradicted4% picked this
The S.S. Coral belongs to the Blue
If the S.S. Coral was a cargo ship that belonged to BSL, it would be over 100 m long, which would mean that it is not eligible to use the dockside facilities of Port Tropica. But we know that it is using those facilities.
4%
Unsupported1% picked this
Port Tropica is served only by
We know that PT is used only by the two lines and only for ships under 100 m long, but we were never told it only serves cargo ships. Both the Blue and Gold Star passenger ships are under 100 m long; they could presumably serve Port Tropica.
1%
Unsupported9% picked this
Port Tropica is not served by ships of the Blue
We know that PT is used only by the two lines and only for ships under 100 m long. Blue Star's cargo ships are too big for PT, because they're over 100 m long, but the Blue Star passenger ships are under 100 m long; they could presumably serve Port Tropica.
9%
Too Strong: all6% picked this
All of the ships of the Blue Star Line are older than any of the ships of
We were never told that cargo and passenger ships are the only two types of ships. So it's possible that BSL and GSL have ships we didn't get any information about. However, even with the information we did get, we learned that most BSL ships were before 1980 and all GSL ships were after 1980. So we could say "most of BSL's cargo and passenger ships are older than any of the cargo and passenger ships of the GSL." But we can't say all of BSL's ships are older. Most of them were built before 1980, but leaves open the possibility that some of them were built last week.
6%

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