Continuing the case in Question 1, the McKinsey & Co. also investigated whether there was any relationship between the type of device that the customers mostly used to access particular e-commerce websites and their willingness to spend on there (in USD). Apart from the other independent variables, namely customers' monthly income, user experience, and number of pageviews, one categorical variable called Device was then added in the survey. This Device variable consists of three types of the mostly-used device: a PC, a smartphone, or a laptop. To incorporate the Device variable into the multiple regression model, 2 dummy variables are introduced: D1 and D2, representing the groups of customers who mostly used smartphones and laptops when accessing the e-commerce website, respectively.

The result of regression analysis is show on the table below. Standard Coeffients Error tStort Pvalue intercept 4.817 3.555 43.792 0.448 income 0.0021 0.0010 2.148 0.006 user experience 5.143 1.464 3.512 0.0065 01 D2 Pageviews 1.902 0.715 2.657 0.026 W 01 11.268 3.536 3.186 0.01 Smartphone 1 0 D2 8.747 8.321 1.051 0.32 M a) Using the above table, write the estimated regression equation to show how the independent variables are associated with the dependent variable (Le. the amount of rmney that the customers are willing to spend on the website). [3 rrlarks] b) For each type of the gev'ges, write the estimated regression equation that shows the relationship between the forementioned independent variables and the dependent variable (y). (Hint: you must write three regression equations in total). [6 malts] c) Using the results in part (b), please determine which device is related to a higher spending of the customers when being used to access the e-corrmerce website. [2 marks] d) Estimate the annunt of money that a customer is willing to spend if his/her monthly income is USD 950, having 2.5 years of experience in online shopping with on average 7 pageviews, and using a laptop to access the e-corrmerce websites. [4 marks] e) Repeating the details in part (d), estimate the amount of money that a customer is willing to spend when accessing the e-cormelte website using mostiy smartphones. Corrpare your result in part (e) with the result in part (d), and write down your conclusion. [5 marks]