It is given that
Mean monthly salary of 20 workers = ₹ 45900
So the total monthly salary = ₹ (20 × 49500) = ₹ 918000
Mean monthly salary of 20 workers and manager = ₹ 49200
So the total monthly salary = ₹ (21 × 49200) = ₹ 1033200
We know that
Manager’s monthly salary = Total monthly salary of 20 workers and manager – Total monthly salary of 20 workers
By substituting the values
Manager’s monthly salary = 1033200 – 918000 = ₹ 115200
Therefore, the manager’s monthly salary is ₹ 115200.