If E₃ = {x ∈ ℕ : x < 20 and x is divisible by 2 or 5}, then what is E₃?
Answer and explanation
Correct answer: {2, 4, 5, 6, 8, 10, 12, 14, 15, 16, 18}
Using ℕ = {1, 2, 3, …}, consider the natural numbers less than 20, so 20 itself is excluded. Multiples of 2 below 20 are 2, 4, 6, 8, 10, 12, 14, 16, and 18. Multiples of 5 below 20 are 5, 10, and 15. Taking the union gives {2, 4, 5, 6, 8, 10, 12, 14, 15, 16, 18}; 10 is listed only once. Thus A is correct.
Frequently asked questions
What is the correct answer to this question?
{2, 4, 5, 6, 8, 10, 12, 14, 15, 16, 18}
Why is this the correct answer?
Using ℕ = {1, 2, 3, …}, consider the natural numbers less than 20, so 20 itself is excluded. Multiples of 2 below 20 are 2, 4, 6, 8, 10, 12, 14, 16, and 18. Multiples of 5 below 20 are 5, 10, and 15. Taking the union gives {2, 4, 5, 6, 8, 10, 12, 14, 15, 16, 18}; 10 is listed only once. Thus A is correct.
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Sets. Topic: Sets and their representations.
