Question: The Evans Department Store has experienced a 4.5 % rate of customer complaints and attempts to lower this rate with an employee retraining program. After the program 850 customers are observed.

a) Assuming that the retraining program has no effect, find the mean and standard deviation and interpret the meaning of the 95 % interval in terms of this problem. Use Binomial Shaft cut formulas.

b) In the observed group of 850 customers, 45 complain. Is this result unusual? Does it seem that retraining was effective?