Multiple choice

If A = {Multiple of 3 between 1 and 20} and B = {Odd natural number less than 14}, which of the following is the union of two sets A and B?

  1. {1, 3, 5, 6, 6, 9, 11, 12, 13, 15, 18}

  2. {1, 3, 5, 6, 7, 9, 11, 12, 13, 15, 9}

  3. {1, 3, 5, 6, 7, 9, 11, 12, 13, 15, 18}

  4. {1, 3, 5, 6, 7, 9, 1, 12, 13, 15, 18}

  5. {1, 3, 5, 6, 9, 9, 11, 12, 13, 15, 18}
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

As per the given information: A = {3, 6, 9, 12, 15, 18} and B = {1, 3, 5, 7, 9, 11, 13} Hence, the union of sets A and B is {1, 3, 5, 6, 7, 9, 11, 12, 13, 15, 18}.

AI explanation

Set A (multiples of 3 between 1 and 20) = {3, 6, 9, 12, 15, 18}. Set B (odd natural numbers less than 14) = {1, 3, 5, 7, 9, 11, 13}. The union combines all elements from both sets without repetition: {1, 3, 5, 6, 7, 9, 11, 12, 13, 15, 18}, which is exactly option C. The other options are wrong due to typos or duplicated/incorrect elements: option A repeats 6 and omits 7 and 13, option B has a stray 9 replacing 7 and a duplicate 9 at the end, option D has a stray 1 instead of 7, and option E has a duplicate 9 and omits 7. Careful element-by-element comparison confirms only the listed correct option matches the true union.

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