Historical sampling data has shown that effluent concentration for ammonia is 2.3 mg/L. Increases to particular agricultural or horticultural activity has caused changes to ammonia concentration into waterways. Let x be a random variable representing ammonia nitrogen concentration in mg/L. Based on recent studies, we may assume that x has a normal distribution with population standard deviation of 0.30. Eight random samples were collected and here are the values: 2.11, 2.5, 2.2, 2.8, 3.0, 2.2, 2.4 and 2.9 The sample mean is 2.51. Construct a statistical test to examine the claim that the concentration has changed from 2.3mg/L. Use level of significance =0.01. a) What is the null hypothesis? What is the alternate hypothesis? b) What is the sample test statistic? Convert the sample mean to a standard z value.