Multiple choice

In the following number series, only one number is wrong. Find out the wrong number. 32, 21, 15.5, 12.75, 11.375, 10.75

  1. 11.375

  2. 15.5

  3. 21

  4. 10.75

  5. 12.75
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D Correct answer
Explanation

The pattern is: 32 - 11 = 21; 21 - 5.5 = 15.5; 15.5 - 2.75 = 12.75; 12.75 - 1.375 = 11.375; 11.375 - 0.6875 = 10.6875. The last term 10.75 is incorrect, as the pattern of subtracting half the previous difference holds.

AI explanation

The pattern of the series halves the difference between consecutive terms at each step. The differences from 32 are 11, 10.5, 2.25, and 1.375, which are generated by subtracting values like 32 - 11 = 21, 21 - 5.5 = 15.5, 15.5 - 2.75 = 12.75, and 12.75 - 1.375 = 11.375. Following this exact pattern of halving differences, the next term should be 11.375 - 0.6875 = 10.6875, making the term 10.75 the wrong number in the sequence.

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