Answer Happy

Question 3 (19 marks) The weather was considered as an important element in the sales pattern of a certain product. Over a period, the average daily temperature was recorded, and the average daily sales of the product were calculated for each temperature. The results were as follows. (Correct all of your answers to 4 decimal places) 12 14 16 18 20 22 24 26 28 30 32 34 Temperature (°C) Average daily sales (in ten units) 105 90 89 88 73 66 55 51 38 41 38 35 (a) State the dependent variable and the independent variable. (2 marks) (b) Plot a scatter diagram of the above data. What does this suggest? (5 marks) (c) Find the correlation coefficient and comment on it. (2 marks) (d) Fit the regression equation, y = a + bx for the above data. (2 marks) (e) Interpret the values of a and b in the regression equation. (2 marks) (f) What proportion of the variability in average daily sales is explained by the temperature? (1 mark) (g) Use the regression equation to estimate the average daily sales if the temperature reaches (i) 10 °C (2 marks) (ii) 25 °C (2 marks) Comment on the reliability for estimating the average daily sales in both cases. (1 mark)