Over the past five years, the average time to resolve customer complaints at Allen Retailing has been 3.4 days. Allen has recently instituted a new complaint processing procedure and tested it on a random sample of 75 complaints. The average time to resolve the complaints in the sample was 2.9 days. Can Allen use this sample result to make the case that the average time for resolving complaints using the new system is less than 3.4 days? State the appropriate decision rule in days. Use a significance level of 5% and a population standard deviation of 1.2 days.

Over the past five years the average time to resolve