For all U.S. students nationally who take the SAT, SAT Reading scores are normally distributed with an average score of 520 for all U.S. students and a population standard deviation of 125. A random sample of 100 students entering Whitmer College had an average SAT Reading score of 515. The sample data can be usedto test the claim that the mean SAT Reading score of all Whitmer College students is different than the national mean SAT Reading score at a 0.05 significance level. What is the test statistic, LaTeX: z_0