A really cool ice cream store owner developed a model to relate to his ice cream shop sales (Y) to the amount of advertising dollars he spent (X1) to the number of extra smiling faces he put on staff for the day (X2) to the degrees in average daily temperature above 70 degrees (X3) ((At 70 degrees X3=)(at 70 degrees X3=0 ) The multiple regression equation for this model is: =$5000 + $500(X1) + $200(X2) + 100(X3) where: = daily sales in ($) X1= advertising dollars spent in $100 increments (for $100 in advertising dollars spent X1 =1) X2= extra staff member in increments of 1 up to 4. Above 4 no more added sales. X3= average daily temperature above or below 70 degrees in one degree increments, (at 70 degrees X3=0)

What is the y-intercept

(a) $5000

b $200

c $100

d None of the above