11th Grade > Mathematics
MATHEMATICAL REASONING MCQs
:
B
Only option C is correct. It is a direct application of Demorgan's law.
∼(p ∨∼q)=∼p ∧∼(∼q)=∼p ∧q
:
B
p: 2 plus 3 is 5
q: Delhi is the capital of India
~p: it is not that 2 plus 3 is five.
Then the given statement is q ∧∼p or ∼p ∧ q
:
A
p: It is snowing
q: I am cold
~q: It is not that I am cold
Then the given statement is p ∧∼q
:
C
A logical statement is a statement which has a definite truth value which is invariant. Here the statement 'you are a boy' depends on who 'you' are. Hence, it is not invariant.
:
C
S(p,q,r)=∼p ∨∼(q ∨ r)S( p, q, r)=∼(∼p) ∨∼(∼q ∨∼r)=p ∨∼(∼(q ∧ r))=p ∨(q ∧ r)
:
D
p: Roses are red
q: The sun is a star
~p: Roses are not red
∼p ∨ q: Roses are not red or the sun is a star
:
D
p: 2+3 =5
q: 8 is less than 10
p ∧ q=∼p ∨∼q
∼p ∨∼q:2+3≠5 or 8 is not less than 10
:
D
The sentence I have failed can have different truth values depending on context. Hence, it is not a statement. Options A and D are false and option B is true.
:
B
The statement can be proved false if we can find a counterexample to the given statement. 2 is a prime number which is even. Hence, the statement is false.
:
A, B, and D
A logical statement is a statement which has a definite truth value which is invariant. Here, options A, B and D have definite truth values. Option C may be true or false for different people.