3.7, 8.7, 23.7, 48.7, 84.7, 128.7

Options

A. 23.7
B. 48.7
C. 84.7
D. 128.7

Explanation

To find the odd one out in the series: 3.7, 8.7, 23.7, 48.7, 84.7, 128.7, we will analyze the differences between the numbers.

### Step-by-Step Solution:

1. **Identify the Series**: The series given is 3.7, 8.7, 23.7, 48.7, 84.7, 128.7.

2. **Extract the Decimal Part**: Notice that all numbers have the same decimal part (0.7). We can focus on the integer parts: 3, 8, 23, 48, 84, 128.

3. **Calculate Differences**:
- Difference between 8 and 3:
\[ 8 - 3 = 5 \]
- Difference between 23 and 8:
\[ 23 - 8 = 15 \]
- Difference between 48 and 23:
\[ 48 - 23 = 25 \]
- Difference between 84 and 48:
\[ 84 - 48 = 36 \]
- Difference between 128 and 84:
\[ 128 - 84 = 44 \]

4. **List the Differences**: The differences we calculated are:
- 5, 15, 25, 36, 44.

5. **Identify the Pattern**: The differences seem to follow a pattern:
- The first difference (5) is \(5 \times 1\),
- The second difference (15) is \(5 \times 3\),
- The third difference (25) is \(5 \times 5\),
- The fourth difference (36) is not fitting the pattern as it should be \(5 \times 7\) which equals 35.
- The fifth difference (44) is not fitting the pattern as it should be \(5 \times 9\) which equals 45.

6. **Determine the Odd One Out**:
- The difference between 48 and 84 should have been 35 (not 36). Thus, 84.7 is the odd one out in the series.

7. **Conclusion**: The wrong number in the series is 84.7. The correct number should be 83.7.

### Final Answer:
The odd one out in the series is **84.7**.