Delhi Police Constable Exam Model Paper 3

Given:
The average monthly salary of a person is 50000.
Formula used:
Sum of observations = average × numbers of observations
Calculation:
Yearly total salary paid $=50000\times 12=600000$
Overtime of 2 months when he earns 6000 extra per month = 2 × 6000 = 12000
∴ Correct yearly salary = 600000 + 12000 = 612000
∴ Correct monthly income of person = 612000 / 12 = 51000
Short trick:
Increase in yearly salary because of overtime of 2 × 6000 = 12000
∴ Increase in monthly salary $=\frac{12000}{12}=1000$
Correct monthly salary $=50000+1000=51000$