1. According to a study, the mean cost of bariatric (weight loss) surgery is $21,500. You think this information is incorrect. You randomly select 25 bariatric surgery patients and find that the mean cost for their surgeries is $20,695. From past studies, the population standard deviation is known to be $2250 and the population is normally distributed. Is there enough evidence to support your claim at a=0.05? 2. Based on a random sample of 20 people, the mean tip that they said they would leave after a $30 meal was $5.00 and the standard deviation was $0.25. Construct a 95%% confidence interval for the population mean. a. Calculate the error of mean. B. Calculate the max error of mean. C. Determine the confidence interval. D. Explain what the confidence interval means in the words of this problem. Apply it. E. Identify the sample size , mean standard deviation, and the appropriate test score (t or z) value of 95%Confidence