Q t' 1 . . . . . . . "as In\" The data In Machineryxlsx shows the data for a manufacturer who IS COnSlClElll'lg replacing machinery records the age of each machine {in months) and the amount spent on repairing each machine {$). Download these data and perform a linear regression in Excel to determine whether age of machinery useful for predicting repair costs. Use the output from your regression and the residual diagnostic plots from this analysis which are given below to answer the questions which follow. Partially correct Mark 7.00 out of 18.00 i? Flag question Histogram of residuals Residual plot I!) r e E o 2 ' .3 D U\" in g .0 at\" E. D N D I llllI -2o -10 0 10 20 6 a 10 12 14 16 18 Residuals Age Answer the following questions by choosing the most correct option or typing the answer: 1. (1 mark) Create a scatterplot of repair cost against age. The relationship shown in the scatterplot is positive 4 2. (1 mark) The histogram of residuals is approximately normally distributedot too skewed : ~l 3. (1 mark) The residual plot shows a random scatter of points for the whole range of ages true V 4. (1 mark) The piece of machinery that is the oldest also has the most repair costs true 6 V 5. {2 marks) The piece of machinery with the largest residual had an age of 10.59 and had a repair cost of 40.044 dollars. Calculate the value of the residual. Type your answer with 3dp. 8 6. {2 marks) The slope of the regression line is equal to [type your answer with 3dp): X A 7. {1 mark) The pvalue for testing the slope of the regression line is less than 0.05. false v X 8. {2 marks) The most appropriate conclusion to the question: Is age a useful predictor of the repair cost of machinery? There is a signicant positive linear relationship between age and repair cost t V 9. {1 mark) The correlation is [type your answer with 3dp): X A 10. {1 mark) Can we predict age when repair cost is 26? No v V 11. {2 marks) Use the regression equation to predict the cost repairing a machine when the machine age is 11. Type your answer with 3dp. X 12. {3 marks) We are 95% confident that for each year older the repair cost decreases 3: between x and 8 dollars. Type your answer with 3dp