Explanation:

- Let's denote the total number of workers as $N$.

- The average salary per head for all workers is Rs8,850.

- The total salary for all workers can be expressed as $N\times 8,850$.

- 9 technicians have an average salary of Rs10,000. So, their total salary is $9\times 10,000=90,000$.

- For the other workers, the average salary is Rs7,780. Let their count be $N-9$.

- Their total salary is $(N-9)\times 7,780$.

- Combining both equations:

$90,000+(N-9)\times 7,780=N\times 8,850$.

- Solving for $N$ gives $N=22$.

Correct option:

- Option 2: 22