Fundamentals of Statistics contains material of various lectures and courses of H. Lohninger on statistics, data analysis and chemometrics......click here for more.


Home Exercises Strontium in Drinking Water
See also: two-sample t-test, survey of exercises 

Exercise
Comparing two sample means

Measuring the concentration of strontium in drinking water in two different areas resulted in the following values:
 

Area 1 (20 sites)
concentrations in mg/l		 Area 2 (18 sites)
concentrations in mg/l
2.88   2.22   0.80   2.60   3.80 
5.50   5.60   2.30   4.40   0.71 
0.91   0.13   3.88   3.20   4.90 
5.12   2.11   0.80   0.90   1.22		 5.54   4.99   4.31   3.52   3.28
4.20   2.33   5.80   3.03   3.77
3.81   2.65   2.36   2.05   2.47
4.22   4.89   3.17

Is there any significant difference in the strontium concentration between areas 1 and 2?  Try to find an answer with an error probability of 1 % and 5 %. Go to the  DataLab  in order to perform the necessary tests (the strontium data will be loaded automatically).
 
 
 
 

Last Update: 2009-Mär-29