An inferior product with an extensive advertising campaign does well when it is released, but sales decline as people discontinue use of the product. If the sales S (in thousands of dollars) after t weeks are given by S(t) =
220t
(t + 6)2
, t ≥ 0
what is the rate of change of sales when
t = 10?
(Round your answer to two decimal places.)
S'(t) =