Find the rate 32. of change in luxury purchases in China with respect to time, in years. \"Estimated values for 2010-2015 McKinsey Insights, China-Wealthy Studies (2008, 2010) Solution To find rate of chaneg we have two points ( 2008, $ 8.2) ( 2015 , $ 27.4) rate of change = ( y2 -y1)/( x2 -x1) = ( 27.4 - 8.2)/( 2015 - 2008) = 19.2/7 = 2.7428 = 2.74.