Mathematics Multiple Choice Questions on “Mathematical Reasoning – New Statements from Old”.
1. The denial of statement is called _____________
a) negation
b) contradiction
c) contrapositive
d) compound
Answer: a
Clarification: The denial of statement is known as negation of the statement. It is denoted by ~p if statement is denoted by p.
2. The negation of a statement is also a statement.
a) True
b) False
Answer: a
Clarification: Yes, the negation of statement is also a statement. If the statement is true, its negation is false or if statement is false, its negation is true.
3. Which of the following cannot be the negation of the statement “Delhi is in India”?
a) Delhi is not in India
b) It is false that Delhi is in India
c) It is false that Delhi is not in India
d) It is not the case that Delhi is in India
Answer: c
Clarification: “Delhi is not in India”, “It is false that Delhi is in India”, “It is not the case that Delhi is in India” are negations of the given statement. Negation of a statement can be formed by adding ‘it is false that’ or ‘it is not the case that’. In statement “It is false that Delhi is not in India” two negation phrases are used which is wrong so it is not the negation statement.
4. Which of the following cannot be the negation of the statement “Everyone in India speaks Hindi”?
a) Not everyone in India speaks Hindi
b) No person in India speaks Hindi
c) Someone in India does not speaks Hindi
d) At least one person in India who does not speaks Hindi
Answer: b
Clarification: Negation of everyone is not everyone. So, negation of the given statement should be “Not everyone in India speaks Hindi”, “Someone in India does not speaks Hindi”, “At least one person in India who does not speaks Hindi”. “No person in India speaks Hindi” cannot be the negation of the given statement as this means no one speaks Hindi which does not means not everyone.
5. Which of the following cannot be the negation of the statement “All angles are equal in equilateral triangle”?
a) There is at least one angle different in equilateral triangle
b) It is false that all angles are equal in equilateral triangle
c) It is not the case that all angles are equal in equilateral triangle
d) All angles are unequal in equilateral triangle
Answer: d
Clarification: Negation of all angles is ‘not all angles’. So, negation of the given statement is “There is at least one angle different in equilateral triangle”, “It is false that all angles are equal in equilateral triangle”, “It is not the case that all angles are equal in equilateral triangle”. But “All angles are unequal in equilateral triangle” cannot be the negation of given statement as this does not include isosceles triangles.
6. Which of the following is not negation of statement “Sum of 2 and 3 is greater than 4”?
a) Sum of 2 and 3 is smaller than 4
b) Sum of 2 and 3 is smaller than or equal to 4
c) Sum of 2 and 3 is not greater than 4
d) It is false that sum of 2 and 3 is greater than 4
