Multiple choice

Choose the pair of the numbers which comes next in the given series: 8, 11, 21, 15, 18, 21, 22, ...

  1. 25, 18

  2. 25, 21

  3. 25, 29

  4. 24, 21

  5. 22, 26
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

This is an alternating addition series, with a random number, 21, interpolated as every third number. The addition series alternates between adding 3 and adding 4. The number 21 appears after each number arrived at by adding 3.

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