LSAT 23 | Section 2 | Logical Reasoning: Q10

LR Question 10 Explanation

QUESTION TEXT: All bridges built from 1950 to 1960 are in serious…

QUESTION TYPE: Must be True

FACTS:

1. Every bridge built during 1950-60 needs serious rehabilitation.
2. Some of these bridges had faulty designs, too.
3. No suspension bridges had faulty design.
4. So some bridges that need rehabilitation aren’t suspension bridges.

ANALYSIS: We can conclude that some bridges with faulty design need serious rehabilitation. (It’s a combination of facts 1 and 2.)

The suspension bridges are just there to confuse you.

___________

1. Even if a suspension bridge was built in 1981, it might need rehabilitation. Maybe every suspension bridge worldwide needs serious rehabilitation. We know every bridge built between 1950-60 needs rehabilitation, but we don’t know that other bridges don’t also need rehabilitation.
2. This is the opposite of A. Maybe no suspension bridge was built between 1950-60, and every suspension bridge worldwide is in perfect condition. We’re not told much about suspension bridges.
3. CORRECT. Some bridges build between 1950-60 have faulty design, and every bridge built between 1950-60 needs serious rehabilitation.
    
   (Including those with faulty design.)
4. The first sentence directly contradicts this answer choice.
5. This is false. We know that some bridges built between 1950-60 have faulty design, and that none of those bridges are suspension bridges. Logically then, those bridges with faulty design must be non-suspension bridges.

Recap: The question begins with “All bridges built from 1950 to 1960 are in serious”. It is a Must be True question. Learn more about LSAT MBT questions in our guide to LSAT Logical Reasoning question types.