Engineering Questions with Answers - Multiple Choice Questions

MCQs on Predicate Logic Quantifiers

1 - Question

. Let P (x) denote the statement “x >7.” Which of these have truth value true?
a) P (0)
b) P (4)
c) P (6)
d) P (9)

View Answer

Answer: d
Explanation: Put x=9, 9>7 which is true.

2 - Question

Let Q(x) be the statement “x < 5.” What is the truth value of the quantification ∀xQ(x), having domains as real numbers.
a) True
b) False

View Answer

Answer: b
Explanation: Q(x) is not true for every real number x, because, for instance, Q(6) is false. That is, x = 6 is a counterexample for the statement ∀xQ(x). This is false.

3 - Question

. Determine the truth value of ∀n(n + 1 > n) if the domain consists of all real numbers.
a) True
b) False

View Answer

Answer: a
Explanation: There are no elements in the domain for which the statement is false.

4 - Question

Let P(x) denote the statement “x = x + 7.” What is the truth value of the quantification ∃xP(x), where the domain consists of all real numbers?
a) True
b) False

View Answer

Answer: b
Explanation: Because P(x) is false for every real number x, the existential quantification of Q(x), which is ∃xP(x), is false.

5 - Question

Let R (x) denote the statement “x > 2.” What is the truth value of the quantification ∃xR(x), having domain as real numbers?
a) True
b) False

View Answer

Answer: a
Explanation: Because “x > 2” is sometimes true—for instance, when x = 3–the existential quantification of R(x), which is ∃xR(x), is true.

6 - Question

The statement,” Every comedian is funny” where C(x) is “x is a comedian” and F (x) is “x is funny” and the domain consists of all people.
a) ∃x(C(x) ∧ F (x))
b) ∀x(C(x) ∧ F (x))
c) ∃x(C(x) → F (x))
d) ∀x(C(x) → F (x))

View Answer

Answer: d
Explanation: For every person x, if comedian then x is funny.

7 - Question

The statement, “At least one of your friends is perfect”. Let P (x) be “x is perfect” and let F (x) be “x is your friend” and let the domain be all people.
a) ∀x (F (x) → P (x))
b) ∀x (F (x) ∧ P (x))
c) ∃x (F (x) ∧ P (x))
d) ∃x (F (x) → P (x))

View Answer

Answer: c
Explanation: For some x, x is friend and funny.

8 - Question

”Everyone wants to learn cosmology.” This argument may be true for which domains?
a) All students in your cosmology class
b) All the cosmology learning students in the world
c) Both of the mentioned
d) None of the mentioned

View Answer

Answer: c
Explanation: Domain may be limited to your class or may be whole world both are good as it satisfies universal quantifier.

9 - Question

Let domain of m includes all students, P (m) be the statement “m spends more than 2 hours in playing polo”. Express ∀m ¬P (m) quantification in English.
a) A student is there who spends more than 2 hours in playing polo
b) There is a student who does not spend more than 2 hours in playing polo
c) All students spends more than 2 hours in playing polo
d) No student spends more than 2 hours in playing polo

View Answer

Answer: d
Explanation: There is no student who spends more than 2 hours in playing polo.

10 - Question

Determine the truth value of statement ∃n (4n = 3n) if the domain consists of all integers.
a) True
b) False

View Answer

Answer: a
Explanation: For n=0, 4n=3n hence, it is true.