Madhya Pradesh Police Exam Model Paper 8

GIVEN:
average of 11 observations = 45
average of 12 observations = 44
FORMULA USED:
average = sum of observations/total number of observations
CALCULATION:
sum of 11 observations $=45\times 11=495$
sum of 12 observations $=44\times 12=528$
12th observation $=528-495=33$
new observation = old average - (difference in average × total observations)
12th observation $=45-\left(1\times 12\right)=33$