Question 8 Hello I need the answers for all parts of this problem please

Homework: Ch... Question 8, 20.CE.31 HW Score: 65.1%, 11.07 of 17 points O Save Part 1 of 3 Points: 0.2 of 1 Men diagnosed with cancer were randomly assigned to either undergo surgery or not. Among the 346 men who had the surgery, 11 eventually died of cancer, compared with 21 of the 349 men who did not have surgery. a) Was this an experiment or an observational study? Explain. b) Create a 90% confidence interval for the difference in rates of death for the two groups of men. c) Based on your confidence interval, is there evidence that surgery may be effective in preventing death from cancer? Explain. re