1. A chemical etching process removes a depth of metal roughly proportional to the time a part spends in the chemical solution. To predict the depth a number of standard parts are left in the solution for various times and the average depth is recorded below: depthvlm) 3.8 4.6 5.3 6.1 7.1 7.8 time(min) 10 10.7 13 15.5 18 17.5 Using your calculator: (a) Find the regression equation which predicts depth as a function of time. (b) What fraction of the variability is explained by the line? Interpret the meaning of the slope. (c) Using the regression equation estimate the depth resulting from subjecting the next part to a 15 minute period. (d) You nd out that the test statistic tiles! = 8.19. Use this value to approximate the p-value (hint: use the t-tablel). (e) Use your approximated p-value to test the validity of the regression model