Day 1


Let’s Recall

Classify the following numbers as Natural Numbers, Whole Numbers and Integers:
12, − 7, 0, 32, − 1, 9

Natural Numbers Whole Numbers Integers
     
Natural Numbers Whole Numbers Integers
12, 32, 9 12, 0, 32, 9 12, − 7, 0, 32, − 1, 9


Classify the following numbers as Even Numbers, Odd Numbers and Prime Numbers:
11, 14, 27, 31, 52, 97, 2

Even Numbers Odd Numbers Prime Numbers
     
Even Numbers Odd Numbers Prime Numbers
14, 52, 2 11, 27, 31, 97 12, − 7, 0, 32, − 1, 9

Important Points

Sets:

  1. A well defined collection of objects is called a set.
  2. Sets are denoted by capital alphabets like A, B, P, Q etc.
    e.g.
    • N = The set of Natural Numbers
    • W = The set of Whole Numbers
    • P = The set of colours in a rainbow
  3. The elements of a set are generally denoted by small alphabets.

Writing a set:

While writing a set,

  1. All the elements are listed in curly brackets.
  2. The elements are separated by commas.
  3. The order in which the elements are written is not important.
  4. Each element is written only once.
  5. e.g.

Number of elements in a set:

Suppose D = {1, 4, 9, 16, 25, 36} is the given set. This set contains 6 elements. The number of elements in set D is represented as n (D) and we can write it as n (D) = 6


Exercise

1. Choose the correct alternative:
  1. Which of the following is a set?
    1. Days of the week
    2. Happy people in your town
    3. Easy problems from the book
    4. Brilliant students in the school
  2. If P represents the set of letters from the word ‘college’, then which of the following represents set P?
    1. {c, o, l, l, e, g, e}
    2. {c, l, e}
    3. {c, o, l, e, g}
    4. {c, o, l, g}
  3. If M = {3, 6, 9, 12, 15, 18}, then (M) = ?
    1. 5
    2. 6
    3. 4
    4. 7

Answers:
  1 - a, 2 - c, 3 - b


2. Write the following sets by listing method:
  1. A is a set of prime numbers between 1 and 20
  2. B is a set of letters in the word ‘cricket’
  3. C is a set of vowels in the English alphabet
  4. D is a set of multiples of 4 less than 50
  5. E is a set of perfect squares between 1 and 50

Answers:

  1. A = {2, 3, 5, 7, 11, 13, 17, 19}
  2. B = {c, r, i, k, e, t}
  3. C = {a, e, i, o, u}
  4. D = {4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44, 48}
  5. E = {1, 4, 9, 16, 25, 36, 49}



This page was last modified on
22 July 2021 at 13:44