Directions: What will come in the place of question mark in following number series?
9.8,10.7,8.9,?,8,12.5

Options

A. 10.7
B. 11.6
C. 10.5
D. 10.9

Answer

To solve the number series: 9.8, 10.7, 8.9, ?, 8, 12.5, we need to identify the pattern in the series.

### Step-by-step Solution:

1. **Identify the first two numbers:**
- The first number is 9.8 and the second number is 10.7.
- To find the difference:
\( 10.7 - 9.8 = 0.9 \)
- This indicates that we are adding 0.9 to the first number.

**Hint:** Look for the difference between consecutive numbers to identify the pattern.

2. **Identify the next pair of numbers:**
- The second number is 10.7 and the third number is 8.9.
- To find the difference:
\( 8.9 - 10.7 = -1.8 \)
- This indicates that we are subtracting 1.8 from the second number.

**Hint:** Continue checking the differences to see if there is a consistent pattern.

3. **Observe the pattern:**
- The first operation was an addition of 0.9 (which is \( 0.9 \times 1 \)).
- The second operation was a subtraction of 1.8 (which is \( 0.9 \times 2 \)).
- It appears that the pattern alternates between adding and subtracting, with the amount being a multiple of 0.9.

**Hint:** Look for a consistent rule in how much is added or subtracted.

4. **Find the next number:**
- The third number is 8.9. Following the pattern, we will add the next multiple of 0.9, which is \( 0.9 \times 3 = 2.7 \).
- Therefore, we calculate:
\( 8.9 + 2.7 = 11.6 \)

**Hint:** Make sure to follow the established pattern of addition and subtraction.

5. **Verify the next operation:**
- Now, we need to check the next number in the series, which is 8.
- We should subtract the next multiple of 0.9, which is \( 0.9 \times 4 = 3.6 \).
- So, we calculate:
\( 11.6 - 3.6 = 8 \)

**Hint:** Always verify your calculations to ensure the pattern holds true.

6. **Final check:**
- The next number after 8 is 12.5. We will add \( 0.9 \times 5 = 4.5 \) to 8.
- So, we calculate:
\( 8 + 4.5 = 12.5 \)

**Hint:** Confirm that the pattern continues to hold with the next numbers in the series.

### Conclusion:
The number that comes in place of the question mark is **11.6**.