The following table shows worldwide sales of a certain type of cell phone and their average selling prices in 2012 and 2013.
Year
2012
2013
Selling Price ($)
385
315
Sales (millions)
740
1,146
(a) Use the data to obtain a linear demand function for this type of cell phone. (Let p be the price, and let q be the demand).
q(p) = -5.8p - 2973
Use your demand equation to predict sales if the price is lowered to $235.
million phones
(b) Fill in the blank.
For every $1 increase in price, sales of this type of cell phone decrease by
million units.