Find the wrong number in the following number series questions.
20.25,23.04,26.01,29.16,32.56,36.00,39.69

Options

A. 36
B. 23.04
C. 32.56
D. 20.25

Answer

To find the wrong number in the series 20.25, 23.04, 26.01, 29.16, 32.56, 36.00, 39.69, we can analyze the pattern based on the square of numbers.

### Step-by-Step Solution:

1. **Identify the Numbers**:
The series is:
- 20.25
- 23.04
- 26.01
- 29.16
- 32.56
- 36.00
- 39.69

2. **Convert to Square Roots**:
Let's find the square roots of these numbers:
- √20.25 = 4.5
- √23.04 = 4.8
- √26.01 = 5.1
- √29.16 = 5.4
- √32.56 = 5.7
- √36.00 = 6.0
- √39.69 = 6.3

3. **Analyze the Pattern**:
The square roots form the sequence:
- 4.5, 4.8, 5.1, 5.4, 5.7, 6.0, 6.3

We can see that each number increases by 0.3:
- 4.5 + 0.3 = 4.8
- 4.8 + 0.3 = 5.1
- 5.1 + 0.3 = 5.4
- 5.4 + 0.3 = 5.7
- 5.7 + 0.3 = 6.0
- 6.0 + 0.3 = 6.3

4. **Identify the Incorrect Number**:
According to the pattern, the square root of the number that should be in place of 32.56 should be 5.7, which means:
- 5.7² = 32.49

However, the series has 32.56 instead of 32.49. Therefore, 32.56 is the wrong number.

5. **Conclusion**:
The wrong number in the series is **32.56**.