A study was done that investigated whether the colour of shirt worn by serving staff at a restaurant influenced if a customer would leave a tip. For the study, researchers randomly assigned 120 customers to be served by an individual wearing a blue shirt (Group 1), and 125 customers to be served by a person wearing a green shirt (Group 2). the people served by someone in a red shirt, 58 of them left a tip. Of the customers served by someone in a black shirt, 40 of them left a tip

1. Create a 95% confidence interval for the difference in the proportion of customers who left a tip after being served by a staff member in a blue shirt versus a green shirt.

2. explain what the interval means in this case

3. Based solely on the confidence interval, is there a difference in the true proportion of customers who leave a tip between the two groups of coloured shirts? If yes, between blue and green which of them usually gets tipped? how do you know?