To find the mean of the data set, we will simply take the average of the data as:
Mean= 345+340+400+625/ 4
= 427.5
So we have mean as, 427.5
Now we have to calculate the variance of the data.
As we know, for variance we take the difference of each value from mean, take its square and then average of all.
- 345-427.5 = -82.5
- 340-427.5 =-87.5
- 400-427.5 = -27.5
- 625-427.5 =197.5
Now
Variance=σ2 =(-82.5)^2 + (-87.5)^2 + (-27.5)^2+ (197.5)^2 /4
σ2=6806.25+7656.25+756.25+39006.25/4
σ2=13556.25
So, the variance is 13556.2
Now we have to calculate the Standard deviation (S.D) of the data.
And the Standard Deviation is just the square root of Variance, so:
σ = √13556.25
σ =116.43
So, the S.D of the data is 116.4
