Answer:
The sample mean year is 1261 A.D.
The standard standard deviation is of 46 A.D.
Explanation:
Sample mean:
Sum of all values divided by the number of values. So
Rounding to the nearest whole number, the sample mean year is 1261 A.D.
Sample standard deviation:
Square root of the sum of the difference squared between each value and the mean, divided by one less than the sample size. So
![s = \sqrt{((1271-1261.4)^2+(1187-1261.4)^2+(1194-1261.4)^2+(1250-1261.4)^2+(1268-1261.4)^2+(1316-1261.4)^2+(1275-1261.4)^2+(1317-1261.4)^2+(1275-1261.4)^2)/(8)} = 45.8]()
Rounding to the nearest whole number, the standard standard deviation year is of 46 A.D.