Questions

(Each question 2 marks)

Take a timed test

21 questions · self-marked practice — reveal the answer and mark yourself.

Question 12 Marks
Find the component statements of the following compound statements and check whether they are true or false. Number 3 is prime or it is odd.
Answer
The component statements are as follows. p: Number 3 is prime. q: Number 3 is odd. Both the statements are true.
View full question & answer
Question 22 Marks
State the converse and contrapositive of each of the following statements: p: A positive integer is prime only if it has no divisors other than 1 and itself.
Answer
Statement p can be written as follows. If a positive integer is prime, then it has no divisors other than 1 and itself. The converse of the statement is as follows. If a positive integer has no divisors other than 1 and itself, then it is prime. The contra positive of the statement is as follows. If positive integer has divisors other than 1 and itself, then it is not prime.
View full question & answer
Question 32 Marks
Find the component statements of the following compound statements and check whether they are true or false. All integers are positive or negative.
Answer
The component statements are as follows. p: All integers are positive. q: All integers are negative. Both the statements are false.
View full question & answer
Question 42 Marks
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.
Answer
The compound statement with ‘And’ is “25 is a multiple of 5 and 8”. This is a false statement, since 25 is not a multiple of 8. The compound statement with ‘Or’ is “25 is a multiple of 5 or 8”. This is a true statement, since 25 is not a multiple of 8 but it is a multiple of 5.
View full question & answer
Question 52 Marks
Which of the following statements are true and which are false? In each case give a valid reason for saying so. r: Circle is a particular case of an ellipse.
Answer
The equation of an ellipse is, $\frac{\text{x}^2}{\text{a}^2}+\frac{\text{y}^2}{\text{b}^2}=1$ If we put a = b = 1, then we obtain $x^2 + y^2 = 1$, which is an equation of a circle Therefore, circle is a particular case of an ellipse. Thus, statement r is true.
View full question & answer
Question 62 Marks
Write the contrapositive and converse of the following statements. You cannot comprehend geometry if you do not know how to reason deductively.
Answer
The contra positive is as follows. If you know how to reason deductively, then you can comprehend geometry. The converse is as follows. If you do not know how to reason deductively, then you cannot comprehend geometry.
View full question & answer
Question 72 Marks
Given statements in (b). Identify the statements given below as contrapositive or converse. If a quadrilateral is a parallelogram, then its diagonals bisect.
  1. If the diagonals of a quadrilateral do not bisect each other, then the quadrilateral is not a parallelogram.
  2. If the diagonals of a quadrilateral bisect each other, then it is a parallelogram.
Answer
  1. This is the contra positive of the given statement.
  2. This is the converse of the given statement.
View full question & answer
Question 82 Marks
Write the contrapositive and converse of the following statements. Something is cold implies that it has low temperature.
Answer
The contra positive is as follows. If something does not have low temperature, then it is not cold. The converse is as follows. If something is at low temperature, then it is cold.
View full question & answer
Question 92 Marks
For each of the following compound statements first identify the connecting words and then break it into component statements. Square of an integer is positive or negative.
Answer
Here, the connecting word is ‘or’. The component statements are as follows. p: Square of an integer is positive. q: Square of an integer is negative.
View full question & answer
Question 102 Marks
Write the following statement in five different ways, conveying the same meaning. p: If a triangle is equiangular, then it is an obtuse angled triangle.
Answer
The given statement can be written in five different ways as follows.
  1. A triangle is equiangular implies that it is an obtuse-angled triangle.
  2. A triangle is equiangular only if it is an obtuse-angled triangle.
  3. For a triangle to be equiangular, it is necessary that the triangle is an obtuse-angled triangle.
  4. For a triangle to be an obtuse-angled triangle, it is sufficient that the triangle is equiangular.
  5. If a triangle is not an obtuse-angled triangle, then the triangle is not equiangular.
View full question & answer
Question 112 Marks
For each of the following compound statements first identify the connecting words and then break it into component statements. All rational numbers are real and all real numbers are not complex.
Answer
Here, the connecting word is ‘and’. The component statements are as follows. p: All rational numbers are real. q: All real numbers are not complex.
View full question & answer
Question 122 Marks
By giving a counter example, show that the following statements are not true.
  1. p: If all the angles of a triangle are equal, then the triangle is an obtuse angled triangle.
  2. q: The equation $x^2– 1 = 0$ does not have a root lying between 0 and 2.
Answer
  1. The given statement is of the form “if q then r”.
q: All the angles of a triangle are equal.
r: The triangle is an obtuse-angled triangle.
The given statement p has to be proved false. For this purpose, it has to be proved that if q, then $\sim\text{r}.$
To show this, angles of a triangle are required such that none of them is an obtuse angle.
It is known that the sum of all angles of a triangle is 180°. Therefore, if all the three angles are equal, then each of them is of measure 60°, which is not an obtuse angle.
In an equilateral triangle, the measure of all angles is equal. However, the triangle is not an obtuse-angled triangle.
Thus, it can be concluded that the given statement p is false.
  1. The given statement is as follows.
q: The equation $x^2 – 1 = 0$ does not have a root lying between 0 and 2.
This statement has to be proved false. To show this, a counter example is required.
Consider $x^2 – 1 = 0$
$x^2 = 1$
$\text{x = }\pm1$
One root of the equation $x^2 – 1 = 0$, i.e. the root x = 1, lies between 0 and 2.
Thus, the given statement is false.
View full question & answer
Question 132 Marks
Find the component statements of the following compound statements and check whether they are true or false. 100 is divisible by 3, 11 and 5.
Answer
The component statements are as follows. p: 100 is divisible by 3. q: 100 is divisible by 11. r: 100 is divisible by 5. Here, the statements, p and q, are false and statement r is true.
View full question & answer
Question 142 Marks
For each of the following compound statements first identify the connecting words and then break it into component statements. x = 2 and x = 3 are the roots of the equation $3x^2 – x – 10 = 0$.
Answer
Here, the connecting word is 'and'. The component statements are as follows. $\mathrm{p}: \mathrm{x}=2$ is a root of the equation $3 \mathrm{x}^2-$ $x-10=0 \mathrm{q}: \mathrm{x}=3$ is a root of the equation $3 \mathrm{x}^2-\mathrm{x}-10=0$
View full question & answer
Question 152 Marks
State the converse and contrapositive of each of the following statements: q: I go to a beach whenever it is a sunny day.
Answer
The given statement can be written as follows. If it is a sunny day, then I go to a beach. The converse of the statement is as follows. If I go to a beach, then it is a sunny day. The contra positive of the statement is as follows. If I do not go to a beach, then it is not a sunny day.
View full question & answer
Question 162 Marks
For each of the following compound statements first identify the connecting words and then break it into component statements. The sand heats up quickly in the Sun and does not cool down fast at night.
Answer
Here, the connecting word is ‘and’. The component statements are as follows. p: The sand heats up quickly in the sun. q: The sand does not cool down fast at night.
View full question & answer
Question 172 Marks
Write the contrapositive and converse of the following statements. If x is a prime number, then x is odd.
Answer
The contra positive is as follows. If a number x is not odd, then x is not a prime number. The converse is as follows. If a number x is odd, then it is a prime number.
View full question & answer
Question 182 Marks
Given statements in (a). Identify the statements given below as contrapositive or converse. If you live in Delhi, then you have winter clothes.
  1. ​If you do not have winter clothes, then you do not live in Delhi.
  2. If you have winter clothes, then you live in Delhi.
Answer
  1. This is the contra positive of the given statement.
  2. This is the converse of the given statement.
View full question & answer
Question 192 Marks
Write the contrapositive and converse of the following statements. x is an even number implies that x is divisible by 4.
Answer
The given statement can be written as follows. If x is an even number, then x is divisible by 4. The contra positive is as follows. If x is not divisible by 4, then x is not an even number. The converse is as follows. If x is divisible by 4, then x is an even number.
View full question & answer
Question 202 Marks
State the converse and contrapositive of each of the following statements: r: If it is hot outside, then you feel thirsty.
Answer
The converse of statement r is as follows. If you feel thirsty, then it is hot outside. The contra positive of statement r is as follows. If you do not feel thirsty, then it is not hot outside.
View full question & answer
Question 212 Marks
Write the contrapositive and converse of the following statements. If the two lines are parallel, then they do not intersect in the same plane.
Answer
The contra positive is as follows. If two lines intersect in the same plane, then they are not parallel. The converse is as follows. If two lines do not intersect in the same plane, then they are parallel.
View full question & answer