To monitor the acid mine pollution from Philsaga Mining Corporation, two independent sampling stations were chosen. One located downstream from the acid mine discharge point and the other located upstream. For 12 monthly samples collected at the downstream station the species diversity index had a mean value of 3.11 and a standard deviation of 0.771, while 10 monthly samples collected at the upstream station had a mean index value 2.04 and a standard deviation of 0.448. What is the value of point estimate? Find a 90% confidence interval for the difference between the population means for the two locations, assuming that the populations are approximately normally distributed. Test the hypothesis that there is no difference between the means using 0.05 level of significance. (Hint: Test the hypothesis of variance first)