What should come in place of question mark (?) in the following number series.
22 19.7 24.3 17.4 ? 15.1

Options

A. 33.1
B. 28.5
C. 26.6
D. 32.7

Answer

To solve the number series: 22, 19.7, 24.3, 17.4, ?, 15.1, we can identify two separate patterns: one increasing and one decreasing.

### Step-by-step Solution:

1. **Identify the two series**:
- The first series consists of the numbers at the 1st, 3rd, and 5th positions: 22, 24.3, and ?.
- The second series consists of the numbers at the 2nd, 4th, and 6th positions: 19.7, 17.4, and 15.1.

2. **Analyze the increasing series**:
- The first number is 22 and the next number is 24.3.
- To find the difference:
\[ 24.3 - 22 = 2.3 \]
- This means we are adding 2.3 to 22 to get 24.3.

3. **Analyze the decreasing series**:
- The first number is 19.7 and the next number is 17.4.
- To find the difference:
\[ 19.7 - 17.4 = 2.3 \]
- This means we are subtracting 2.3 from 19.7 to get 17.4.

4. **Continue the decreasing series**:
- The next number in this series is 17.4 and the next number is 15.1.
- To find the difference:
\[ 17.4 - 15.1 = 2.3 \]
- This confirms that we are consistently subtracting 2.3.

5. **Find the missing number**:
- Since we are adding 2.3 to 24.3 to find the next number in the increasing series:
\[ ? = 24.3 + 2.3 = 26.6 \]

6. **Conclusion**:
- The number that should come in place of the question mark (?) is 26.6.

### Final Answer:
The answer is 26.6.