Unfortunately, arsenic occurs naturally in some ground water (Reference: Union Carbide Technical Report K/UR-1). A mean arsenic level of = 8.0 parts per billion (ppb) is considered safe for agricultural use. A well in Texas is used to water cotton crops. This well is tested on a regular basis for arsenic. A random sample of 37 tests gave a sample mean of = 7.2 ppb arsenic, with = 1.9 ppb. Does this information indicate that the mean level of arsenic in this well is less than 8 ppb? Use = 0.01. a) What is the level of significance? State the null and alternative hypotheses. b) What sampling distribution will you use? Explain the rationale for your choice of sampling distribution. How many degrees of freedom will we use (if appropriate)? c) Compute the appropriate sampling distribution of the sample test statistic. d) Find the critical value. e) Based on your answers in parts (a) through (d), will you reject or fail to reject the null hypothesis? Are the data statistically significant at level ? e) Interpret your conclusion in the context of the application