A training program is being used in the customer help department of an electronics company. Prior to the training, 25 employees were tested on their knowledge of troubleshooting procedures. Once the training was completed, the same employees were tested again in an effort to determine whether the training program was effective. Which set of hypotheses is appropriate to determin if the training had an impact on scores?
a) H0: μ1 - μ2 = 0,
b) H1: μ1 - μ2 ≠ 0
c) H0: μD = 0,
d) H1: μD ≠ 0
e) H0: π1 - π2 = 0,
f) H1: π1 - π2 ≠ 0