A recruiter for Big Box stores has collected data summarizing the amount of money the company spent on print, web, and TV advertising in Texas over the past $22$ months and the resulting number of applications received from job applicants during the same months. The recruiter would like to build a regression model to predict the number of applications the company should expect based on a given advertising mix.

$2$a$)$ If the recruiter wanted to build a regression model using only one independent variable $($X$1,$ X$2,$ or X$3)$ to predict the number of applications received, what variable should be used and why? Use the Excel Regression Data Analysis tool.

$2$b$)$ Suppose the recruiter chooses to use the regression function with all independent variables X$1,$ X$2$ and X$3.$ What is the estimated regression function and R$-$square? Use the Excel Regression Data Analysis tool.

$2$c$)$ Suppose the recruiter wants to spend $$5,000$ on print, $$1000$ on web, and $$3,500$ on TV ads. What is the predicted number of applications? Use the Excel Trend$()$ function.

$ Print $($X$1)$ $ Web $($X$2)$ $ TV $($X$3)$ Applications $4,8009903,3205764,4301,8505,3407694,2604,9206,5801,1934,2604,0809,3601,2394,7901,4302,6605311,8002,9904,7206653,1004,7101,6807631,0901,7804,3605083,6301,3509,5608712,2004,2709,5401,1632,8304,7009,1801,2006702,1602,7804203,6001,0004,5805391003,9306,8808271,4103,3209,7409723702,0009,4407602,6402,0707,7408014,6903707,9407407608901,7002088701,3609002142,7305101,1802641,7502,7901,340459$