Addition Rules for Variances

Topic Page

Questions

• If you add two independent random variables, what is the standard deviation of the combined distribution, if the standard deviations of the two original distributions were, for example, 7 and 5?
• What is the procedure for calculating the new standard deviation for two combined random variables, if the random variables X and Y are not independent?
• If you multiply each entry of a set by 3 and added 1, how would the mean and standard deviation change?
• If I know the mean, standard deviation, and size of sample A and sample B, how do I compute the standard deviation of the union of samples A and B? What if samples A and B are of different sizes?
• Can you find the standard deviation of negative numbers?
• What is the difference between the standard deviation and margin of error?
• Can a sample have a standard deviation of zero?
• If you are calculating the standard deviation of measurements, how do you determine how many significant figures to use?
• Question #d281c
• A data set has a variance of 0.16. What is the standard deviation of the data set?
• How do I calculate the variance and standard deviation of 102, 104, 106, 108, 110?
• What is the variance of 2, 9, 3, 2, 7, 7, 12?
• How do you find the variance and standard deviation of {2,3,4,6,8,9}?
• The sum of all X's is 3780. The sum of all X^2 is 80000. The sample N = 180. How can I calculate the variance?
• What Excel formula do I use to calculate the variance between two cells?
• How do you find the sample variance in 89, 57, 104, 73, 26, 121, 81?
• How do you find the mean of the random variable #x#?
• How do you find the mean of the random variable #x#?
• He following table shows the probability distribution for a discrete random variable. What is the variance of X?
• How do I find the variance in 40; 56; 59; 60; 60; 62; 65; 69; 75; 84 statistics?
• What is the difference between variance and variability?
• How do you find the variance of the data 2, 4, 6, 8, 10?