Find the z-score corresponding to a score of X=23 for each of the following distributions. Show the formulas used and plug in the numbers for each u (population) and o (standard deviation) value (show all steps).
a. u = 20 and o = 7
b. u = 42 and o = 12
c. u = 76 and o = 23
d. u = 17 and o = 15