Demand for Smart Phones The following table shows worldwide sales of smart...

Demand for Smart Phones The following table shows worldwide sales of smart phones and their average wholesale prices in 2009 and 2010:

a. Use the data to obtain a linear demand function for smart phones, and use your demand equation to predict sales to the nearest million phones if the price was set at $155.

b. Fill in the blanks: For every ____ increase in price, sales of smart phones decrease by ___ units.