What is the set P₁ = {x : x ∈ N, x is a multiple of 5 or 7, and x < 30}?
Answer and explanation
Correct answer: P₁ = {5, 7, 10, 14, 15, 20, 21, 25, 28}
The positive multiples of 5 less than 30 are 5, 10, 15, 20, and 25. The positive multiples of 7 less than 30 are 7, 14, 21, and 28. Since “or” means that either condition may hold, combine both lists and remove repetitions. The result is option A; 30 is excluded because the inequality is strict.
Frequently asked questions
What is the correct answer to this question?
P₁ = {5, 7, 10, 14, 15, 20, 21, 25, 28}
Why is this the correct answer?
The positive multiples of 5 less than 30 are 5, 10, 15, 20, and 25. The positive multiples of 7 less than 30 are 7, 14, 21, and 28. Since “or” means that either condition may hold, combine both lists and remove repetitions. The result is option A; 30 is excluded because the inequality is strict.
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Sets. Topic: Sets and their representations.
