Which of the following sets are finite or infinite
(i) The set of months of a year
(ii) {1, 2, 3, . . .}
(iii) {1, 2, 3, . . .99, 100}
(iv) The set of positive integers greater than 100
(v) The set of prime numbers less than 99

Solution:

(i) The set of months of a year is a finite set because it has a finite number (12) of elements.

(ii) {1, 2, 3 …} is an infinite set as it has infinite (which we cannot count) number of natural numbers.

(iii) {1, 2, 3 …99, 100} is a finite set because the numbers from 1 to 100 are finite in number (100).

(iv) The set of positive integers greater than 100 is an infinite set because positive integers greater than 100 are infinite (which we cannot count) in number.

(v) The set of prime numbers less than 99 is a finite set because prime numbers less than 99 are finite in number (25)

NCERT Solutions Class 11 Maths Chapter 1 Exercise 1.2 Question 2

Which of the following sets are finite or infinite? (i) The set of months of a year (ii) {1, 2, 3 ...} (iii) {1, 2, 3 ... 99, 100} (iv) The set of positive integers greater than 100 (v) The set of prime numbers less than 99 

Summary:

We are asked to find which of the following sets are finite or infinite. We found that
(i) The set of months of a year is a finite set.
(ii) {1, 2, 3 ...} is an infinite set.
(iii) {1, 2, 3 ... 99, 100} is a finite set.
(iv) The set of positive integers greater than 100 is an infinite set.
(v) The set of prime numbers less than 99 is a finite set.