The level of dissolved oxygen in a river indicates the water’s ability to support aquatic life. A research project is started to determine if the oxygen levels in the river have changed. A study done...

The level of dissolved oxygen in a river indicates the water’s ability to support aquatic life. A research project is started to determine if the oxygen levels in the river have changed. A study done 10 years prior, showed that the mean oxygen levels in milligrams per liter for the river was 4.3.

A.) Write appropriate hypotheses for this test

B.) Water is collected samples from 15 randomly chosen locations along the river and measured the dissolved oxygen. Construct and interpret a 95% confidence interval for the mean dissolved oxygen level for this stream. The results are in milligrams per liter:

C.) Based on the sample from part B, conduct a significance test of these results using a 5% significance level. Give complete results of the test including a p-value and what the results means.