The average salary, per head, of all the workers of an institution is 60. The average salary of 12 officers is = 400; the average salary, per head, of the rest is 56. The total number of workers in the institution is

Let the total number of members in the institution be z

average = $$\frac{SumofElements}{NumberofElements}$$

Average salary of institution = Rs 60

total salary of Institution =Rs 60z

Given that out of z persons , there are 12 officers and there average salary is = Rs 400

and so total salary of 12 officers = 12 x 400 =Rs 4800

So total salary of other (z-12) members =Rs ( 60z - 4800 )..............(1)

It is given that average salary of (z-12) persons = Rs 56

and hence from here the total salary of (z-12) people = Rs 56(z-12)..........(2)

Equation 1 and 2 are equal

60z - 4800 = 56z - 672

4z = 4128

z = 1032