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Analysis of several plant food preparations for potassium ion yielded the following data: Sample 1 2 3 4 5

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%K 5.15, 5.03, 5.04, 5.18, 5.20 7.18, 7.17, 6.97 4.00, 3.93, 4.15, 3.86 4.68, 4.85, 4.79, 4.62 6.04, 6.02, 5.82, 6.06, 5.88

a) Find the mean and standard deviations for each sample b) Obtain pooled value spooled The inside diameter of an open cylindrical tank was measured. The results of 4 replicate measurements were 5.4, 5.2, 5.5 and 5.2m. Measurements of the height of the tank yielded 9.8, 9.9 and 9.6m. Calculate the volume in L of the tank and the standard deviation of the result.

Sewage and Industrial pollutants dumped into a body of water can reduce the dissolved oxygen concentration and adversely affect aquatic species. In one study, weekly readings are taken from the same location in a river over a 2-month period. Week Number 1 2 3 4 5 6 7 8

The homogeneity of chloride level in a water sample from a lake was tested by analysing portions drawn from the top and from the near the bottom of the lake with the following results in ppm Cl:

Dissolved O2 (ppm) 4.9 5.1 5.6 4.3 4.7 4.9 4.5 5.1

Week 3 value is suspected to be an outlier. Use Q-test to determine if the value can be rejected at the 95% confidence level.

Top 26.30 26.43 26.28 26.19 26.49

Bottom 26.22 26.32 26.20 26.11 26.42

Check if Chloride levels are homogeneous all throughout at 95% confidence level.

Two different analytical methods were used to determine residual chlorine in sewage effluents. Both methods were used on the same samples, but each sample came from various locations with differing amounts of contact time with the effluent. The concentration of Cl in mg/L was determined by the two methods and the following results were obtained: Sample 1 2 3 4 5 6 7 8

Method A 0.39 0.84 1.76 3.35 4.69 7.7 10.52 10.92

Method B 0.36 1.35 2.56 3.92 5.35 8.33 10.70 10.91

What type of test should be used to determine if the two methods give different results? Do they?