Step-by-step explanation:
the average change rate for a function g(x) is defined for an interval of x values as
(g(interval end) - g(interval begin))/(interval end - interval begin)
in our case that is
(g(2013) - g(2008))/(2013 - 2008) =
= (24 mil. - 186 mil)/5 = -162 mil./5 =
= -162,000,000 / 5 = -32,400,000
that means that as a mean value there were 32,400,000 digital cameras shipped less every year.
in other words, fewer and fewer digital cameras are sold. the demand is strongly declining.
actually, following the mean values and their trend, there should have been no new digital cameras shipped in 2014 anymore (as 24 mil. - 32.4 mil is less than 0).
