Definition of Sets

Q.

A set is a collection of ___ objects.

Q.

The collection of intelligent students in a class is

1. A null set

2. A singleton set

3. A finite set

4. Not a well defined collection

Q. If you were left alone by your classmates, how would you feel?

Q.

Find (a) of (i) (ii) (b) of (i) (ii)

Q.

Which of the following collections are sets?

Healthy students in your class

Q.

Match the following: $\begin{array}{cc}\text{Column A}& \text{Column B}\\ 1.\{1,2,4,8\}& A.\left\{\text{x: x is a natural even number less than 10}\right\}\\ 2.\left\{2\right\}& B.\left\{\text{x: x is a prime number and a divisor of 8}\right\}\\ 3.\{2,4,6,8\}& C.\left\{\text{x: x is a divisor of 8}\right\}\\ 4.\{4,6,8,9\}& D.\{\text{x: x is a composite number less than 10}\}\end{array}$

1. 1 - C, 2 - A, 3 - B, 4 - D

2. 1 - B, 2 - D, 3 - A, 4 - C

3. 1 - A, 2 - D, 3 - C, 4 - B

4. 1 - C, 2 - B, 3 - A, 4 - D

Q.

If A={2, 4, 6, 8}, then 7 ____ A.

1. does not belong to

2. belongs to

3. is an element of

4. is a subset of

Q.

Write the given set in roster form A={Whole numbers less than 7}.

Q. What is the additive identity for a number x?

1. 0
2. -x
3. x
4. 1

Q.

Check the given collection is set? If not a set, give reason

Good football players

Q.

Find:

(i) of (a) (b) (c)

(ii) of (a) (b) (c)

Q.

Which of the following collections are sets?

Your classmates coin collection

Q. Question 6 (i)
A teacher wanted to analyze the performance of two sections of students in a mathematics test of 100 marks. Looking at their performances, she found that a few students got under 20 marks and a few got 70 marks or above.So she decided to group them into intervals of varying sizes as follows : 0−20, 20−30…60−70, 70 − 100. Then she formed the following table:
$$\begin{array}{cc}Marks& Numberofstudent\\ 0-20& 7\\ 20-30& 10\\ 30-40& 10\\ 40-50& 20\\ 50-60& 20\\ 60-70& 15\\ 70-above& 8\\ Total& 90\end{array}$$
(i) Find the probability that a student obtained less than 20% in the mathematics
test.

Q.

Which of the following collections are sets?

Fruits sold in the supermarket close to your house

Q. Is the collection of all the states of India a set? Give reasons to support your answer.

Q. What is the additive identity for a number x?

1. x
2. 1
3. 0
4. -x

Q. If each of the following pairs represents a pair of equivalent rational numbers, find the values of x:
(i) $\frac{2}{3}\mathrm{and}\frac{5}{x}$
(ii) $\frac{-3}{7}\mathrm{and}\frac{x}{4}$
(iii) $\frac{3}{5}\mathrm{and}\frac{x}{-25}$
(iv) $\frac{13}{6}\mathrm{and}\frac{-65}{x}$

Q. There are $15$ fruits in a basket. The basket contains $a$ number of apples, $g$ number of grapes and $k$ number of kiwis only. What would be the value of $a+g+k?$

1. $10$
2. $12$
3. $15$
4. $18$