A random sample of street vendors in a certain city yielded the following data on their earnings from street vending (annual income in dollars), their age (years), and how many hours they typically work at street vending per day.

1. Write down the regression model for annual earnings as a quadratic function of age. Be sure to define the variables you use in the model. Ignore hours worked per day for this analysis.

2. Use Minitab fit the model to the data. Request a normal probability plot of the residuals and a plot of the residuals vs. fits.

Earnings Age Hours 29 12 21 2841 1876 2934 1552 3065 3670 2005 3215 1930 2010 3111 2882 1683 1817 4066 62 18 40 50 65 44 17 70 20 29 15 14 33 8 10 10 11 11 5 8 8 6 9 9 5 7 12