157.5 45 15 6 3 2 1

Options

A. 1
B. 2
C. 6
D. 157.5

Explanation

To solve the problem of identifying the odd one out in the series: 157.5, 45, 15, 6, 3, 2, 1, we need to analyze the pattern of the numbers.

### Step-by-Step Solution:

1. **Identify the Series**: The series given is 157.5, 45, 15, 6, 3, 2, 1.

2. **Check for a Pattern**: We need to see how each number relates to the next. A good approach is to check if each number is being divided by a certain factor to get the next number.

3. **Divide the First Two Numbers**:
- Divide 157.5 by 45:
\[ \frac{157.5}{45} = 3.5 \]

4. **Divide the Next Pair**:
- Divide 45 by 15:
\[ \frac{45}{15} = 3 \]

5. **Continue with the Next Pair**:
- Divide 15 by 6:
\[ \frac{15}{6} = 2.5 \]

6. **Next Division**:
- Divide 6 by 3:
\[ \frac{6}{3} = 2 \]

7. **Next Division**:
- Divide 3 by 2:
\[ \frac{3}{2} = 1.5 \]

8. **Final Division**:
- Divide 2 by 1:
\[ \frac{2}{1} = 2 \]

9. **Analyze the Results**:
- The results of the divisions are: 3.5, 3, 2.5, 2, 1.5, and 2.
- Notice that the pattern shows a consistent decrease in the divisor, but when we reach the last division, instead of getting a 2, we have a 1.

10. **Identify the Odd One Out**:
- The last number in the series is 1, which does not fit the pattern established by the previous divisions. According to the pattern, after 2, we should have 2 instead of 1.

11. **Conclusion**:
- Therefore, the odd one out in the series is **1**. It should be replaced by **2** to maintain the pattern.