A standardized test, designed to measure the mathematical skill level of seventh graders is said to have a mean score (µ) = 75 with a standard deviation (σ) = 10. As the principal of a private school, you're curious how seventh graders, in your school compare. Selecting a sample of 25 students from your school and administering the mathematical skill test, you discover a sample mean (X) of 79. Assume that you're working at the .05 level of significance.
a. State an appropriate null hypothesis.
b. What is the value of the calculated test statistic (Z)?
c. State your conclusion.