Multiple choice

Directions: Find the missing term in the following series. 11, ___, 41, 81, 161

  1. 16

  2. 21

  3. 26

  4. 31

  5. 36
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B Correct answer
Explanation

The pattern is: 11*2-1=21, 21*2-1=41, 41*2-1=81, 81*2-1=161. The missing term is 21.

AI explanation

The pattern in the series multiplies the previous term by 2 and then subtracts 1 to get the next term. Applying this to the term 41 gives 41 multiplied by 2, which equals 82, and subtracting 1 gives 81. Following the same rule backwards from 41, we divide by 2 after adding 1 to 41, which means 42 divided by 2 equals 21; therefore, the missing term is 21.

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