Calculate the Mean and StandardDeviation of a list: 140,120,100,80,60. Okay the answers should be - mean = 100, standard deviation = 28.28, variance = 800. I can't understand why Mathematica says the standard deviation is 31.6228 and the variance is 1000. The formula for variance in the documentation is the same as my spreadsheet formula, I can't understand why the result is different. Please help out a new user and tell me where I am going wrong.