STAT 2060 Lecture : Calculating Variance

• School: University of Guelph
• Department: Statistics
• Course: STAT 2060
• Professor: Peter Kim

Document Summary

To calculate the variance, you need to use two formulas: for the mean and the variance. That is, the variance is defined as 2 = e(x2) -( e(x))2 = e(x2) - 2, then we can calculate e(x2). E(x2)= x2 ipi = 12*p(1) +22*p(1) + 32 *p(3)+ 42 *p(3)+ 52 *p(3)+ 62 *p(3)= In order to find p(1) and p(3), use the fact that pi =1 and e(x)= xipi. =e(x)= xipi = 1*p(1) +2*p(1) + 3 *p(3)+ 4*p(3)+ 5*p(3)+ 6*p(3)=3p(1) +18p(3). So, you can compute p(3)=( -1. 5)/ 12 and p(1)=0. 5- 2p(3); then, calculate.