question archive In June 2012 chemical analyses were made of 12 water samples (each of unit volume) taken from various parts of a city lake, and the measurements of chlorine content were recorded
In June 2012 chemical analyses were made of 12 water samples (each of unit volume) taken from various parts of a city lake, and the measurements of chlorine content were recorded
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In June 2012 chemical analyses were made of 12 water samples (each of unit volume) taken from various parts of a city lake, and the measurements of chlorine content were recorded. During the next two winters, the use of road salt was substantially reduced in the catchment areas of the lake. In June 2014, 18 water samples were analyzed and their chlorine contents were recorded. Summary statistics are as follows:2012 2014Sample meanSample varianceSample size18.3 17.81.44 3.2412 18(a) Do the data provide strong evidence that there is a reduction of average chlorine level in the lake water in 2012 compared to the level in 2014?(b) State the underlying assumption(s).
