1. Deviation = The sum of the variables on each side of the mean will add up to 0 X 9+3 8+2+5 60 5-5 2-4

2. Weighted Mean There are times when we want to know the mean of several means Section 1=85N 1 =28 Section 2=72N 2 =28 Section 3=79N 3 =28 ++ 3 85+72+73 3 236 3 78.67

3. Section 1=85N 1 =95 Section 2=72N 2 =25 Section 3=79N 3 =18 Weighted Mean Number in a particular group Mean of a particular group Number in all groups combined

4. Section 1=85N 1 =95 Section 2=72N 2 =25 Section 3=79N 3 =18 95(85)+25(72)+18(79) 138 8075+1800+1422 138 11297 138 =81.86

5. Section 1=80N 1 =14 Section 2=29N 2 =76 Section 3=75N 3 =19 14(80)+76(29)+19(75) 109 1120+2204+1425 109 4749 109 43.57