In the following question, the sentence given with blank to be filled in with an appropriate word. Select the correct alternative out of the four and indicate it by selecting the appropriate option. The meeting was presided _____ by the Chairman.
The average salary of all workers in a workshop is Rs.12000. The average salary of 7 technicians is Rs.15000 and the average salary of the rest is Rs.9000. The total number of workers in the workshop is