Mean of peak expiratory flow for children without asthma is 306. Investigator wants to see whether children with chronic bronchitis have restricted peak expiratory flow or not. A sample of 40 kids with chronic bronchitis are examined, and their mean peak expiratory flow is 279. Standard deviation is 7.1. Do children with chronic bronchitis have lower expiratory flow ? Alpha = 0.05. What is the null and alternate hypothesis? What is the test statistic?