Explanation:

- Let's understand the pattern of the series: 9.8, ?, 8.9, 11.6, 8, 12.5

- Look closely and observe:

- The sequence alternates between subtraction and addition.

- 9.8 and 11.6 have a difference of +2.8.

- 8.9 and 8 have a difference of -0.9.

- 8 and 12.5 have a difference of +4.5.

- Now identify the missing number:

- The pattern involves alternately adding and subtracting increasingly larger numbers.

- From 9.8, add +0.9 to get 10.7.

- Based on this logic, the correct replacement for the question mark is 10.7.

Option 1: 10.7