A cleaning service firm recently began to outsource some of its workload. In an effort to see what impact outsourcing had on customer satisfaction, it sent a series of surveys to a randomly selected sample of recent clients. The sample of 100 clients gave an average customer satisfaction rating of 4.5 with a standard deviation of 1. The firm wants to know if this result is meaningfully different from their benchmark score of 4.0. 

Calculate standarderror for mean customer satisfaction and provide a 95% confidence interval . Rating is atleast ____ and not more than _____.