What is the average of: 2 1/2, 3 1/2 and 4 1/4?

Answer for 10 points show work you guys in advanced < 3

8.74 rounded to the nearest whole number

Me its important ! marge runs an ice cream parlor. her speciality is triple chocolate sundaes. she can prepare 1 sundae every 2 minutes, and she earns $1.20 for each sundae she makes . if she just makes sundaes for a single shift of at most 4 hours and at least 2 hours , which function relates her earnings to the number of minutes she works?