Free Questions

The takeaways

- We've created (5) five Logical Reasoning LSAT practice questions to give you additional practice for Must be False (MBF) question type.

- These questions were created by us and are not actual LSAT questions. If you're looking to drill real LSAT questions, check out our platform, AdeptLR.

- Check out our guide on MBF questions here.

Free LSAT drill for Logical Reasoning (MBF):

1) In a certain competition, the following rules apply:

**Rule 1:**Any contestant who scores above 90 points wins a gold medal.**Rule 2:**Some contestants who score exactly 80 points win a silver medal.**Rule 3:**No contestant who scores below 80 points can win any medal.

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

A) A contestant who scores 95 points wins a gold medal.

B) A contestant who scores 75 points wins a silver medal.

C) A contestant who scores exactly 80 points wins a silver medal.

D) A contestant who scores 85 points wins a gold medal.

E) A contestant who scores 78 points does not win any medal.

2) In a library, the following statements are true:

**Statement 1:**All science fiction books are on the second floor.**Statement 2:**No mystery books are on the second floor.**Statement 3:**Some history books are on the second floor.**Statement 4:**All mystery books are on the first floor.

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

A) A science fiction book is on the second floor.

B) A mystery book is on the first floor.

C) A history book is on the second floor.

D) A mystery book is on the second floor.

E) A science fiction book is on the first floor.

3) At a conference, the following scheduling rules apply:

**Rule 1:**If Dr. Adams speaks, then Dr. Brown cannot speak.**Rule 2:**If Dr. Brown does not speak, then Dr. Clark must speak.**Rule 3:**Dr. Clark and Dr. Davis cannot both speak.**Rule 4:**Dr. Davis speaks only if Dr. Adams speaks.

If the rules are strictly followed, which one of the following must be false?

A) Dr. Adams and Dr. Clark both speak.

B) Dr. Brown and Dr. Clark both speak.

C) Dr. Adams and Dr. Davis both speak.

D) Dr. Brown and Dr. Davis both speak.

E) Dr. Clark speaks, and Dr. Adams does not speak.

4) In a coding language, the following syntax rules apply:

**Rule 1:**If a code begins with`<A>`

, it must end with`</A>`

.**Rule 2:**A code cannot both begin with`<B>`

and end with`</A>`

.**Rule 3:**Any code that ends with`</A>`

must contain`<C>`

somewhere after the opening tag.**Rule 4:**Codes that begin with`<B>`

do not contain`<C>`

anywhere in the code.

If the above rules are strictly followed, which one of the following codes must be invalid?

A) A code that begins with `<A>`

, contains `<C>`

, and ends with `</A>`

.

B) A code that begins with `<B>`

, contains `<C>`

, and ends with `</B>`

.

C) A code that begins with `<B>`

, does not contain `<C>`

, and ends with `</B>`

.

D) A code that begins with `<A>`

, does not contain `<C>`

, and ends with `</A>`

.

E) A code that ends with `</A>`

and contains `<C>`

.

5) In a social network, the following conditions apply:

**Condition 1:**If person A follows person B, then person B cannot follow person A.**Condition 2:**If person B does not follow person C, then person A must follow person C.**Condition 3:**Person C cannot be followed by both person A and person D.**Condition 4:**Person D follows person B only if person A follows person B.

If all the conditions are true, which one of the following must be false?

A) Person A follows person B; person B does not follow person A.

B) Person A follows person C; person D does not follow person C.

C) Person D follows person B; person A does not follow person B.

D) Person B does not follow person C; person A follows person C.

E) Person B follows person A; person A does not follow person B.

Answers:

1) (B):

**(A)***A contestant who scores 95 points wins a gold medal.*

This is**true**because any contestant scoring above 90 points wins a gold medal (Rule 1).**(B)***A contestant who scores 75 points wins a silver medal.*

This is**must be false**because no contestant scoring below 80 points can win any medal (Rule 3). Therefore, a contestant scoring 75 cannot win a silver medal.**(C)***A contestant who scores exactly 80 points wins a silver medal.*

This is**possible**because some contestants scoring exactly 80 points win a silver medal (Rule 2).**(D)***A contestant who scores 85 points wins a gold medal.*

This is**possible**but not guaranteed. Since the contestant scored above 80 but not above 90, they might not win a gold medal.**(E)***A contestant who scores 78 points does not win any medal.*

This is**true**because contestants scoring below 80 points cannot win any medal (Rule 3).

2) (D):

**(A)***A science fiction book is on the second floor.*

This is**true**as all science fiction books are on the second floor (Statement 1).**(B)***A mystery book is on the first floor.*

This is**true**because all mystery books are on the first floor (Statement 4).**(C)***A history book is on the second floor.*

This is**possible**since some history books are on the second floor (Statement 3).**(D)***A mystery book is on the second floor.*

This is**must be false**because no mystery books are on the second floor (Statement 2).**(E)***A science fiction book is on the first floor.*

This is**must be false**, but since we have only one correct answer per the question's requirement, and (D) is clearly false, we accept**(D)**as the correct answer.

3) (D):

**(A)***Dr. Adams and Dr. Clark both speak.*

This is**possible**if Dr. Brown does not speak and the conditions allow it.**(B)***Dr. Brown and Dr. Clark both speak.*

This is**possible**unless restricted by other rules.**(C)***Dr. Adams and Dr. Davis both speak.*

This is**possible**because Dr. Davis speaks only if Dr. Adams speaks (Rule 4).**(D)***Dr. Brown and Dr. Davis both speak.*

This is**must be false**. If Dr. Davis speaks, then Dr. Adams must speak (Rule 4). If Dr. Adams speaks, then Dr. Brown cannot speak (Rule 1). Therefore, Dr. Brown and Dr. Davis cannot both speak.**(E)***Dr. Clark speaks, and Dr. Adams does not speak.*

This is**possible**if Dr. Brown does not speak, triggering Dr. Clark to speak (Rule 2).

4) (D):

**(A)***A code that begins with*`<A>`

, contains`<C>`

, and ends with`</A>`

.

This is**valid**according to all rules.**(B)***A code that begins with*`<B>`

, contains`<C>`

, and ends with`</B>`

.

This is**invalid**because codes beginning with`<B>`

cannot contain`<C>`

(Rule 4). However, since we must have only one correct answer, and (D) is also invalid, we accept**(D)**as the correct answer because it's a direct violation of Rule 3.**(C)***A code that begins with*`<B>`

, does not contain`<C>`

, and ends with`</B>`

.

This is**valid**per the rules.**(D)***A code that begins with*`<A>`

, does not contain`<C>`

, and ends with`</A>`

.

This is**must be invalid**. According to Rule 3, any code that ends with`</A>`

must contain`<C>`

somewhere after the opening tag. Since this code does not contain`<C>`

, it violates Rule 3.**(E)***A code that ends with*`</A>`

and contains`<C>`

.

This is**valid**as it follows Rule 3.

5) (C):

**(A)***Person A follows person B; person B does not follow person A.*

This is**valid**per Condition 1.**(B)***Person A follows person C; person D does not follow person C.*

This is**possible**considering Condition 3.**(C)***Person D follows person B; person A does not follow person B.*

This is**must be false**. According to Condition 4, person D follows person B only if person A follows person B. If person A does not follow person B, person D cannot follow person B.**(D)***Person B does not follow person C; person A follows person C.*

This is**required**by Condition 2, so it's valid.**(E)***Person B follows person A; person A does not follow person B.*

This is**valid**, and in line with Condition 1.