mean and standard devition
in Statistics Answers by

Your answer

Your name to display (optional):
Privacy: Your email address will only be used for sending these notifications.
Anti-spam verification:
To avoid this verification in future, please log in or register.

1 Answer

If I understand this correctly the summation of each datum minus 50 is 123.5 and the summation of the same difference squared is 238.4 and there are 100 data in the set. So I would say that 50 is a weighted factor which is subtracted from each datum. The actual sum of the data would then be 100*50+123.5=5123.5 and the mean is 5123.5/100=51.235. The variance is the sum of the squares of the differences of each datum and the mean, but we have the sum of the squares of the differences of each datum and 50, which is not the mean.

Let's call S1 summation(x-50)^2 and S2 summation(x-51.235)^2. S1=238.4, so we need S2 to calculate the variance. The square root of the variance will be the standard deviation. Variance=S2/100 and SD=sqrt(S2)/10. If x1, x2, x3, ..., x100 represent the dataset:




Therefore, S2=S1-152.5225=238.4-152.5225=85.8775.

The variance is 0.858775 and SD=0.9267.

by Top Rated User (788k points)

Related questions

0 answers
asked Jun 8, 2013 in Statistics Answers by anonymous | 1.6k views
0 answers
Welcome to, where students, teachers and math enthusiasts can ask and answer any math question. Get help and answers to any math problem including algebra, trigonometry, geometry, calculus, trigonometry, fractions, solving expression, simplifying expressions and more. Get answers to math questions. Help is always 100% free!
85,445 questions
90,983 answers
103,530 users