Independent random samples from regions in Tara gave the following phosphorous measurements (in ppm). Assume the population distributions of phosphorous are mound-shaped and symmetric for this region....

Independent random samples from regions in Tara gave the following phosphorous measurements (in ppm).
Assume the population distributions of phosphorous are mound-shaped and symmetric for this region.
Region: ?; ? = 12


580   810  790  790  340  800   890  860   840   640   970   720

d. Find a 90% confidence interval for ?.
e. Interpret your result in (d).