### Still have math questions?

A company introduces a new product for which the number of units sold $$S$$ is given by the equation below, where $$t$$ is the time in months
$$S ( t ) = 110 ( 7 - \frac { 9 } { 2 + t } )$$
(a) Find the average rate of change of $$S ( t )$$ during the first year. (b) During what month of the first year does $$S ^ { \prime } ( t )$$ equal the average rate of change?