An intern is working for Pacific TV (PTV), a small cable and
Internet provider, and has proposed some questions that might be
used to assess how much customers are willing to pay for a new PTV
service. The intern got a set of 12 with a mean of $60.2 and a
standard deviation of $14.5. How many customers the intern should
interview if PTV asks for 90% confidence within 4 units?
A) 36
B) 144
C) 170
D) 43