Concentrations of dis solved Oxygen in ppm 

Site 1 
Site 2 
Site 3 
Site 4 
Totals 

X 
X squ. 
X 
X squ. 
X 
X squ 
X 
X squ. 

Field Readings 
10 
100 
8.8 
77.44 
9 
81 
11.8 
139.24 

9.8 
96.04 
10.8 
116.64 
7 
49 
11.2 
125.44 

10.3 
106.09 
9 
81 
7.6 
57.76 
9 
81 

10 
100 
9 
81 
7.2 
51.84 
8.4 
70.56 

Sum X 
40.1 
37.6 
30.8 
40.4 

Sum X squared 
402.03 
356.08 
239.6 
416.24 

Mean 
10 
9.4 
7.7 
10.1 

(Sum X) squared/n 
402 
353.44 
237.16 
408.04 

Sum x squared 
0.13 
2.64 
2.44 
8.2 
13.41 

n (number of readings) 
4 
4 
4 
4 

degrees of freedom 
3 
3 
3 
3 
12 

Pooled s squared 
1.12 

Standard Deviation 
0.747 

Level of Significant Difference (5%) 
1.63 
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