Please provide full detail including how the z-table lookup is determined.
2. The article "Reliability of Domestic Waste Biofilm Reactors" (J. of Envir. Engr., 1995: 785-790) suggests that substrate concentration (mg/cm^3) of influent to a reactor is normally distributed with  = 0.30 and  = 0.06.
a. What is the probability that the concentration exceeds 0.40?
b. What is the probability that the concentration is at most 0.25?
c. How would you characterize the largest 10% of all concentration levels?
Please provide full detail.