use excel spreadsheet

1. A study was conducted on the effect of nitric acid dilutions on the accelerated weathering of wood. The acid pH levels of 20,25,30,35, and 40 were tested with distilled water (pH 5.6) used as a control. An accelerated weathering chamber was used with times of 200, 400, 600, 800, and 1000 hours Red cedar wafers of approximately 700 mg were obtained and weighed accurately for the start weight at the beginning of the experiment At the end of the accelerated time, the wafers are again weighed for the final weight. The resulting data, including the difference in start weight and final weight are given in the following table: Differenc pH Time Sun W. Final Obs. No . 2 300 66 667 621 601 575 29 79 91 4 5 6 7 * 200 20 656 36 112 w 10 11 400 656 43 63 13 14 15 617 10 30 30 30 10 15 35 15 1000 300 400 679 101 19 4 57 17 19 20 21 35 677 IN 100 23 51 25 100 695 56 36 642 33 56 7 NO 1000 9 56 a. Fit a multiple linear regression model with weight difference as the response variable and time and pll as the regressor variables b. Test for significance of regression. Be sure to write out your hypotheses and conclusion c. Analyze the residuals. Is there any indication that the data may not satisfy the assumptions for the regression and associated tests? Explain why or why not d. Construct a 90% CI for each regressor variable coefficient. What do the results indicate? e. Test for significance of each B. Based on these results, do you think both of the regressor variables are needed in this model? Why or why not? 1. A study was conducted on the effect of nitric acid dilutions on the accelerated weathering of wood. The acid pH levels of 2.0, 2.5, 3.0, 3.5, and 4.0 were tested with distilled water (pH 5.6) used as a control. An accelerated weathering chamber was used with times of 200, 400, 600, 800, and 1000 hours. Red cedar wafers of approximately 700 mg were obtained and weighed accurately for the start weight at the beginning of the experiment. At the end of the accelerated time, the wafers are again weighed for the final weight. The resulting data, including the difference in "start weight and final weight" are given in the following table: Differenc Oh No phi Time Start W. Final W 1 200 600 700 692601 91 20 20 $ 1000 595 20 7 677 656 632 612 9 10 11 12 BO NO 1000 6.97 3.0 697 43 30 w 636 14 15 617 101 30 35 35 1000 200 14 59 17 18 19 20 21 35 35 1000 200 100 100 IN 37 31 64 40 40 25 1000 300 700 IX 5.6 56 56 5.6 46 0 00 29 20 a. Fit a multiple linear regression model with weight difference as the response variable and time and pH as the regressor variables b. Test for significance of regression. Be sure to write out your hypotheses and conclusion 6. Analyze the residuals. Is there any indication that the data may not satisfy the assumptions for the regression and associated tests? Explain why or why not d. Construct a 90% CI for each regressor variable coefficient. What do the results indicate e. Test for significance of each B. Based on these results, do you think both of the regressor variables are needed in this model? Why or why not