Madhya Pradesh Police Exam Model Paper 6

Given:
Average of 11 numbers = 28
Average of first 5 numbers = 23
Average of next 5 numbers = 25
Formula used:
Sum of observations = Average × Number of observations
Calculation:
Sum of 11 numbers $=28\times 11$
⇒ 308
Sum of first 5 numbers $=23\times 5$
⇒ 115
Sum of next 5 numbers $=25\times 5$
⇒ 125
Total sum of first 10 numbers $=\left(115+125\right)$
⇒ 240
11th number $=\left(308\mathit{–}240\right)$
⇒ 68
∴ The 11th number is 68