Q18 - All of the Cargo Ships

[Mr.kevincourtney]

I could not find an answer I liked and still do not understand why A is correct.

I diagrammed like this:

BSL Cargo Ship ---> Over 100 meters long
BSL Pass. Ship ---> Under 100 meters long

BSL Ships --m--> Built before 1980

GSL Ships ---> Built after 1980 and under 100 meters long

Port T. ---> accommodates ships under 100 meters long

S.S. Coral is docked in Port T.

Couldn't the S.S. Coral be a BSL Pass. Ships which was built before 1980?

On this must be true question, I don't understand the correct answer.

[fmuirhea]

You're missing something relevant in the last sentence: "The S.S. Coral is a cargo ship that is currently docked at Port Tropica." So, no, it cannot be a BSL passenger ship. Even if you didn't assume that cargo ships and passenger ships were mutually exclusive, the conditionals about BSL ships force you to that conclusion. If there were a BSL ship that was classified as both a passenger ship and a cargo ship, it would have to be both over and under 100 meters long - an impossibility.

Your diagramming is correct. Here's how you get to (A):

S.S. Coral --> currently docked at Port Tropica --> less than 100 meters long --> not BSL cargo --> GSL cargo (because we know it's a cargo ship and PT is only open to ships from BSL and GSL) --> built after 1980

(B) must be false based on the statements - we can actually deduce that the S.S. Coral belongs to the GSL.

(C), (D), and (E) are all things that could be true, but are not provable.

For (C), we know that PT serves only BSL and GSL, and we know that there is at least one cargo ship currently there (i.e., the S.S. Coral), but we don't know anything about the other ships it serves, so this could be true or false.

For (D), I believe the statement, "Port Tropica, which is open only to ships of these two lines (i.e., BSL and GSL)" could be interpreted to mean that it only serves those from GSL, but it is not definitive. Then again, you might interpret this statement to mean that it definitely serves ships from both lines, which would make (D) another MBF. No matter which interpretation you go with, this answer choice does not have to be true.

For (E), we know that most (but not necessarily all) BSL ships were built before 1980 and all GSL were built after 1980, but the term "most" isn't strong enough to warrant the term "all" in the answer choice.

[Mr.kevincourtney]

That obviously makes a huge difference! My eyes must have drifted right over those important words.

Thanks for the help!