If M = {x ∈ ℕ : x ≤ 50 and x is a multiple of 10}, how many elements are in M?
Answer and explanation
Correct answer: 5
The positive natural-number multiples of 10 that are less than or equal to 50 are 10, 20, 30, 40, and 50. The endpoint 50 must be included because the inequality is ≤, not <. Hence M = {10, 20, 30, 40, 50}, and counting its distinct members gives 5. Therefore, option B is correct. The other numerical choices result from omitting an endpoint or confusing the count with the common difference.
Frequently asked questions
What is the correct answer to this question?
5
Why is this the correct answer?
The positive natural-number multiples of 10 that are less than or equal to 50 are 10, 20, 30, 40, and 50. The endpoint 50 must be included because the inequality is ≤, not <. Hence M = {10, 20, 30, 40, 50}, and counting its distinct members gives 5. Therefore, option B is correct. The other numerical choices result from omitting an endpoint or confusing the count with the common difference.
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Sets. Topic: Sets and their representations.
