Logical Connectives - Intermediate Level: logical operators INTERMEDIATE

Master logical connectives concepts through this excellence pursuit practice set. Worksheet 16 of 30 contains 20 intermediate-level problems. Deep dive into logical operators while learning AND-OR-NOT logic, conditional statements, logical connectives. Recommended for mid-level learners aiming for moderate complexity with mixed patterns.

📝 Worksheet 16 of 30 â€Ē 20 questions â€Ē ⏱ïļ Estimated time: 20 minutes â€Ē ðŸŽŊ Intermediate level

What you'll learn in this worksheet:
Your progress through Logical Connectives
Worksheet 16 of 30 (53% complete)

Question 1

In set theory, what logical connective matches this concept? A âˆĐ B = ∅ (disjoint sets)
Disjoint means no element is in both, which is NOT (A AND B).

Answer: Ž(x ∈ A ∧ x ∈ B)

Question 2

In set theory, what logical connective matches this concept? A ⊆ B (A is subset of B)
Subset means IF element is in A, THEN it must be in B, which is implication.

Answer: x ∈ A → x ∈ B

Question 3

Identify the logical fallacy in this argument: "If you study, you'll pass. You didn't study, so you won't pass." What fallacy is being committed?
Fallacy of denying the antecedent. Form: If P then Q, not P, therefore not Q. You might still pass without studying.

Question 4

Consider the conditional statement: "If p: You press the button, then q: The light turns on" (p → q) If p is True and q is False, what is the truth value of p → q?
Step 1: Understand the implication (→) operator
The implication p → q is False ONLY when p is True but q is False.
In all other cases, it is True.

Truth table for p → q:
p=T, q=T → Result=T
p=T, q=F → Result=F (the only False case)
p=F, q=T → Result=T
p=F, q=F → Result=T

Step 2: Apply the given values
p = True, q = False

Step 3: Evaluate p → q
Since p is True but q is False, the implication fails: p → q = False

Question 5

Consider the statement: 'Neither John nor Mary came' If p is T and q is T, what is the truth value of 'Neither John nor Mary came'?
Step 1: Understand 'neither...nor' statements
'Neither p nor q' means 'not p AND not q'
Logical form: Žp ∧ Žq

Step 2: Build the truth table
Žp ∧ Žq is True ONLY when both p and q are False
Truth table:
p=T, q=T → ®T ∧ ®T = F ∧ F = F
p=T, q=F → ®T ∧ ®F = F ∧ T = F
p=F, q=T → ®F ∧ ®T = T ∧ F = F
p=F, q=F → ®F ∧ ®F = T ∧ T = T

Step 3: Apply given values
p = T, q = T
ÂŽp = F, ÂŽq = F
Žp ∧ Žq = F

Answer: False

Question 6

In set theory, what logical connective matches this concept? The intersection of sets A and B
Intersection means element is in BOTH sets, which is logical AND.

Answer: x ∈ A ∧ x ∈ B

Question 7

Consider the relationship between: P: Having oxygen Q: Fire burning Is P a necessary condition, sufficient condition, both, or neither for Q?
Step 1: Understand necessary and sufficient conditions
â€Ē P is NECESSARY for Q: Q cannot be true without P (Q → P)
â€Ē P is SUFFICIENT for Q: P being true guarantees Q (P → Q)
â€Ē P is BOTH: P if and only if Q (P ↔ Q)

Step 2: Analyze the relationship
P: Having oxygen
Q: Fire burning

Step 3: Determine the condition type
Fire needs oxygen (necessary), but oxygen alone doesn't guarantee fire (not sufficient)

Answer: Necessary but not sufficient

Question 8

Find a counterexample to show this statement is FALSE: "p → q is logically equivalent to q → p" Provide truth values for p, q, r that make the two sides different.
Implication is not symmetric. Converse is not equivalent to original.

p=True, q=False: p→q=False, q→p=True → Different!

Question 9

Consider this syllogism: Premise 1: All mammals are animals. Premise 2: All dogs are mammals. Therefore, all dogs are animals. Is this syllogism logically valid?
This is valid: If A ⊆ B and B ⊆ C, then A ⊆ C. All dogs (A) are mammals (B), all mammals (B) are animals (C), so all dogs (A) are animals (C).

Question 10

Consider the conditional statement: "If p: The temperature drops below 0°C, then q: Water freezes" (p → q) If p is False and q is True, what is the truth value of p → q?
Step 1: Understand the implication (→) operator
The implication p → q is False ONLY when p is True but q is False.
In all other cases, it is True.

Truth table for p → q:
p=T, q=T → Result=T
p=T, q=F → Result=F (the only False case)
p=F, q=T → Result=T
p=F, q=F → Result=T

Step 2: Apply the given values
p = False, q = True

Step 3: Evaluate p → q
Since this is not the case where p is True and q is False, p → q = True

Question 11

Complete the truth table for the expression: (p ∧ q) → r What is the truth value when p=T, q=F, r=F?
Step 1: Break down the expression
Expression: (p ∧ q) → r
Given: p=T, q=F, r=F

Step 2: Evaluate inner expressions first
p ∧ q = T ∧ F = F

Step 3: Evaluate outer expression
(F) → F = True
Remember: Implication is False only when antecedent is True and consequent is False

Question 12

Evaluate this logical argument: Premise: If it rains, the ground gets wet. Premise: The ground is NOT wet. Therefore, it is NOT raining. Is this argument valid? (If the premises are true, must the conclusion be true?)
Argument form: Modus Tollens

This is Modus Tollens: If P → Q and ®Q are true, then ®P must be true.

Conclusion: This argument is VALID.

Question 13

Consider the conditional statement: "If p: You press the button, then q: The light turns on" (p → q) If p is False and q is True, what is the truth value of p → q?
Step 1: Understand the implication (→) operator
The implication p → q is False ONLY when p is True but q is False.
In all other cases, it is True.

Truth table for p → q:
p=T, q=T → Result=T
p=T, q=F → Result=F (the only False case)
p=F, q=T → Result=T
p=F, q=F → Result=T

Step 2: Apply the given values
p = False, q = True

Step 3: Evaluate p → q
Since this is not the case where p is True and q is False, p → q = True

Question 14

Are the following two logical expressions equivalent? Expression 1: p → q Expression 2: ®q → ®p Answer Yes or No and explain why.
Step 1: Understand what logical equivalence means
Two expressions are logically equivalent if they have the same truth value for ALL possible combinations of variables.

Step 2: Analyze the expressions
Expression 1: p → q
Expression 2: ®q → ®p

Step 3: Apply Contrapositive equivalence
A conditional statement and its contrapositive are ALWAYS equivalent.
If p → q, then ®q → ®p is also true.
These expressions ARE equivalent.

Question 15

Identify the logical fallacy in this argument: "If we allow students to redo tests, next they'll want to rewrite all exams, then abolish grades entirely!" What fallacy is being committed?
Assumes without evidence that one small step leads to extreme consequences.

Question 16

Logic puzzle: Three people, A, B, and C, are each either a knight (always tells truth) or knave (always lies). A says: 'B is a knave.' B says: 'A and C are the same type.' C says: 'A is a knight.' What are A, B, and C (or A and B)?
Case analysis: If A knight → B knave (A's truth) → A and C different (B's lie) → C knight? But C says 'A is knight' which would be true, consistent. Wait, need full check.

Actually solve: Assume A knight → 'B knave' true → B knave → B's statement 'A and C same' is false → A and C different → C knave → C says 'A knight' which is false (since A knight?) Contradiction.

Therefore A knave → 'B knave' false → B knight → B's statement true → A and C same → C knave → C says 'A knight' false (since A knave) ✓. Solution: A knave, B knight, C knave.

Question 17

Consider the relationship between: P: Being a triangle Q: Having three sides Is P a necessary condition, sufficient condition, both, or neither for Q?
Step 1: Understand necessary and sufficient conditions
â€Ē P is NECESSARY for Q: Q cannot be true without P (Q → P)
â€Ē P is SUFFICIENT for Q: P being true guarantees Q (P → Q)
â€Ē P is BOTH: P if and only if Q (P ↔ Q)

Step 2: Analyze the relationship
P: Being a triangle
Q: Having three sides

Step 3: Determine the condition type
A shape is a triangle if and only if it has three sides

Answer: Necessary and sufficient

Question 18

Identify the logical fallacy in this argument: "If we allow students to redo tests, next they'll want to rewrite all exams, then abolish grades entirely!" What fallacy is being committed?
Assumes without evidence that one small step leads to extreme consequences.

Question 19

Given: p âˆĻ q, ÂŽp What can you validly derive?
Rule: Disjunctive Syllogism

If P âˆĻ Q is true and P is false, then Q must be true.

Answer: q

Question 20

In set theory, what logical connective matches this concept? Elements NOT in set A
Complement means element is NOT in the set, which is logical NOT.

Answer: Ž(x ∈ A)
Previous Worksheet Next Worksheet