A researcher is investigating wants to know if people enrolled in a new stress reduction program report the same stress levels as the national average. They measure the stress levels of a sample of 30 participants enrolled in the program. The mean stress level of the sample is 70. The national average stress score is 75, and the standard deviation is 10. 

a) State the null and a two-tailed null hypothesis for a single-sample z-test for the researcher's question (1 point)

b) What is the Z test statistic for a single sample Z test here? (0.5 points) 

c) Would you reject the null hypothesis here? Explain your answer thoroughly (0.5 points)