Bihar Police Constable Model Paper 4

Given:
Average of 27 numbers = 12
Average of first 13 numbers = 11
Average of last 13 numbers = 13
Formula used:
Sum of observations = average × Number of observations
Calculation:
Sum of 27 numbers = 12 × 27
⇒ 324
Sum of first 13 numbers = 11 × 13
⇒ 143
Sum of last 13 numbers = 13 × 13
⇒ 169
Total sum of first 13 numbers and last 13 numbers = (143 + 169)
⇒ 312
Now, 14th number = (324 – 312)
⇒ 12
∴ The 14th number is 12