What type of set is A = {x ∈ ℕ : x is a two-digit natural number}?
Answer and explanation
Correct answer: Finite and n(A) = 90
The two-digit natural numbers begin at 10 and end at 99, inclusive. To count consecutive integers in an inclusive interval, use last number − first number + 1. Thus the number of elements is 99 − 10 + 1 = 90. Since the list has a definite first and last term, it is finite. Therefore A is a finite set with n(A) = 90.
Frequently asked questions
What is the correct answer to this question?
Finite and n(A) = 90
Why is this the correct answer?
The two-digit natural numbers begin at 10 and end at 99, inclusive. To count consecutive integers in an inclusive interval, use last number − first number + 1. Thus the number of elements is 99 − 10 + 1 = 90. Since the list has a definite first and last term, it is finite. Therefore A is a finite set with n(A) = 90.
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Sets. Topic: The Empty Set, Finite and Infinite Sets, Equal Sets.
