The Mann-Whitney U test is a non-parametric alternative to the student's t- test and measures the likelihood that a randomly selected value from sample set i will be significantly different from a randomly selected value from sample set 2. When testing for a significant lowering in the value of a parameter in sample set 2. the U test counts the total number of occasions for which any value in set 2 is higher than any value in set 1. The null hypothesis can be rejected if the calculated U value so derived is less than or equal to a test statistic. Use the Mann-Whitney U test to determine if protein precipitation has significantly reduced the concentration of Mg\" ions in six independent samples of human blood plasma (see the data in Table 1 below and then answer all four questions a} to d}]. Table T concentration of lag" in uglml In Concentration of Hg" in up'ml In In human plasma prior to nrotoln human puma after mtoln proclpftoon proclpitoon