RRB Group-D Model Paper 13 with answers for online practice

Given:
The average salary of the entire staff = Rs. 15000
The average salary of officers = Rs. 45000
The average salary of non-officers = Rs. 10000
Number of officers = 20
Calculations:
Let the number of non-officers be x.
Total member in entire staff = x + 20
Total salary of the entire staff = (x + 20) × 15000
⇒ 15000x + 300000 ----(1)
Total salary of officers = 20 × 45000 = 900000
Total salary of non-officers = x × 10000 = 10000x
Total salary of the entire staff = 900000 + 10000x ----(2)
From equation (1) and (2)
⇒ 10000x + 900000 = 15000x + 300000
⇒ 5000x = 600000
⇒ x = 120