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Published on: 28/09/2019
Mathematical Reasoning
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Questions + Answers key
Take MCQ Mathematics Test

1.
Given below are two statements
p: 25 is a multiple of 5
q: 25 is a multiple of 8
Write the compound statements connecting these two statements with "and" and "or". In both cases check the validity of the compound statement.
2.
Rewrite each of the following statements in the form "p if and only if q"
(i) p: If you watch television, then your mind is free and if your mind is free, then you watch television.
(ii) q: For you to get an A grade, it is necessary and sufficient that you do all the homework regularly.
(iii) r: If a quadrilateral is equiangular, then it is a rectangle and if a quadrilateral is a rectangle, then it is equiangular.
3.
Write each of the statements in the form "if p then q"
(i) p: It is necessary to have a password to log on to the server.
(ii) q: There is traffic Jam whenever it rains.
(iii) r: You can access the website only if you pay a subscription fee.
4.
Write the negation of the following statements:
(i) p: For every positive real number x, the number x - 1 is also positive.
(ii) q: All cats scratch.
(iii) r: For every real number x, either x > 1 or x < 1.
(iv) s: There exists a number x such that 0 < x
5.
Check the validity of the following statements
(i) 100 is a multiple of 2 and 5.
(ii) Square of an integer is positive or negative.
6.
Write the contrapositive and converse of the following statements.
(i) If you were born in India, then you are a citizen of India.
(ii) If a triangle is equilateral then it is isosceles.
(iii) If x is an even number then x is divisible by 4
7.
Write each of the following statements in the form "if-then"
(i) You earn a living implies you work.
(ii) A number is even only if it is a multiple of 2.
(iii) To pass in examination it is necessary that you work hard.
8.
State whether the 'or' used in the following statements is "exclusive" or "inclusive". Give reasons for your answer.
(i) A rectangle is a quadrilateral or a pentagon.
(ii)A square is a polygon or a parallelogram.
9.
For each of the following compound statements first identify the connecting words and then break it into component statements.
(i) The sun is cold and the moon rotates around the earth.
(ii)The school works or a holiday is declared.
(iii) Ankita is rich or happy
10.
Find the component statements of the following compound statements and check whether they are true or false.
(i)The sun shines or it rains.
(ii)India is a democracy and a monarchy.
11.
Write the negation of the following statements:
(i) Every natural number is greater than 0.
(ii) The sum of 4 and 6 is 10.
(iii) A whole number is an integer.
12.
Write down the compound statements by using 'and','or' of the following statements
p : It is cold
q : It is raining
13.
Rewrite the following statement with 'if-then' in five different ways conveying the same meaning 'If a natural is odd, then its square is also odd'.
14.
Find the conditional statement of 'You will get a sweet dish after the dinner'.
15.
Write down the truth bvalue of each of the following statements.
(i) Delhi is in India
(ii) Chennai is in Pakistan
(iii) 5 + 6 = 11
1.
The compound statement with "and " is
25 is a multiple of 5 and 8.
Since p is true and q is false, so the compound statement with "and" is not true.
Thus the statement" p and q" is not valid.
Now the compound statement with "or" is
25 is a multiple of 5 or 8. Since p is true and q is false, so the compound statement with "or" is true Thus the statement "p or q" is valid.
2.
(i) You watch television if and only if your mind is free.
(ii) You get an A grade if and only if you do all the homework regularly.
(iii) A quadrilateral is equiangular if and only if it is a rectangle.
3.
(i) If you log on to the server, then you have a password.
(ii) If it rains, then there is traffic jam.
(iii) If you can access the website, then you pay a subscription fee
4.
(i) ~ p: There exists a positive real number x such that x-I is not positive.
(ii) ~ q: There exists a cat which does not scratch.
(iii) ~ r: There exists a real number x such that neither x > 1 nor x < l.
(iv) ~ s: There does not exist a number x such that 0 < x < l.
5.
(i) Component statements of the compound statement are
p: 100 is a multiple of 2
q: 100 is a multiple of 5
Now both p and q are true. Thus the given compound statement is valid.
(ii) The component statements of the compound statement are
p: Square of an integer is positive.
q: Square of an integer is negative.
Let us assume that p is false
\(\therefore \) x2< 0 for x \(\in \) Z
q is true
So when p is false, q is true.
Thus the given compound statement is valid.
6.
(i)Here p: You were born in India.
q: You are a citizen of India.
Now ~ p: You were not born in India.
~ q: You are not a citizen of India.
The contrapositive of the given statement is:
If you are not a citizen of India then you were not born in India.
The converse of the given statement is:
If you are a citizen of India then you were born in India.
(ii)Here p: A triangle is equilateral.
q: A triangle is isosceles.
Now ~ p : A triangle is not equilateral.
\(\sim \)q: A triangle is not isosceles
The contrapositive of the given statement is:
If a triangle is not isosceles then it is not equilateral.
The converse of the given statement is:
If a triangle is isosceles then it is equilateral.
(iii)Here p: x is an even number.
q: x is divisible by 4.
Now ~ p: x is not an even number.
\(\sim \)q: x is not divisible by 4.
The contrapositive of the given statement is:
If x is not divisible by 4 then x is not an even number.
The converse of the given statement is:
If x is divisible by 4 then x is an even number
7.
(i) If you earn a living then you work.
(ii) If a number is even then it is multiple of 2.
(iii) If you wish to pass in examination you must work hard.
8.
(i)This statement makes use of exclusive 'or'. Since a geometrical figure can not be a quadrilateral and also a pentagon.
(ii) This statement makes use of inclusive 'or'. Since a geometrical figure can be a polygon as well as a parallelogram.
9.
(i)The component statement has the connecting word 'and'. Component statements are
p: The sun is cold.
q: the moon rotates around the earth.
(ii)The component statement has the connecting word 'or'. Component statements are
p: The school works.
q: A holiday is declared.
(iii)The component statement has the connecting word 'or'. Component statements are.
p: Ankita is rich.
q: Ankita is happy
10.
(i)The component statements are
p: The sun shines
q: it rains Both the component statements p and q are true.
(ii) The component statements are
p: India is a democracy
q: India is a monarchy
The component statement p is true whereas the component statement q is false.
11.
(i) Negation of statement is: There exists a natural number which is not greater than 0.
(ii) Negation of statement is: The sum of 4 and 6 is not equal to 10.
(iii) Negation of statement is: A whole number is not an integer
12.
The conjunction of the statement p and q is given by
\(p\wedge q\) : It is cold and it is raining
The disjunction of the statement p and q is given by
\(p\vee q\) : It is cold and it is raining
13.
The component statements of the given statement are
p : A natural number is odd
q : Square of a natural number is odd.
The given statement is 'if p then q'.
It can be expressed in five different ways as follows
(i) p\(\Rightarrow \)q i.e. x is an odd natural number \(\Rightarrow \) x2 is an odd natural number.
(ii) P is a sufficient condition for q i.e. knowing that a natural number is odd is sufficient to conclude that its square is odd.
(iii) p only if q i.e. a natural number is odd only if its square is odd.
(iv) q is necessary condition for p i.e. when a natural number is odd, its square is necessarily odd.
(v) \(\sim \)q\(\Rightarrow \sim \)p i.e. if the square of a natural number is not odd, then the natural number is not odd.
14.
The conditional statement of given statement is 'If you take dinner, then you will get a sweet dish.'
15.
(i) T, because statement 'Delhi is in India' is true
(ii) F, because statement 'Chennai is in pakistan' is false
(iii) T, becuse statement '5 + 6 = 11' is true
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