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### Question

In the following number series, one of the numbers does not fit into the series. Find the wrong number.

5, 7.5, 11.25, 17.5, 29.75, 50, 91.25

**A**

7.5

**B**

17.5

**C**

29.75

**D**

91.25

**Soln.**

**Ans: c**

Number 29.75 is wrong and should be replaced by 28.75 . The series is: 5 + (1.25 X 2) gives 7.5, 7.5 + (1.25 X 3) gives 11.25, then 11.25 + (1.25 X 5) gives 17.5, then 17.5 + (1.25 X 9) gives 28.75, then 28.75 + (1.25 X 17) gives 50, then 50 + (1.25 X 33) gives 91.25. The multipliers of 1.25 increase by 1, 2, 4, 8, 16