A company introduces a new product for which the number of units sold Ss given by the equation below, where t is the time in months.

Question

s(t) = 155(7-(9/(2+t)))

a) Find he average rate of change of s(t) during the first year.
I got the answer to be 1395/28

b) During what month of the first year does s'(t) equal the average rate of change?
I checked my work and kept getting ~3, which is March, but website is still counting it wrong. Any ideas??

Any help is greatly appreciated!

Answer 1

I agree with the average rate of change. So, you want

s'(c) = 1395/28

s'(t) = 1395/(t+2)^2

so,

1395/(c+2)^2 = 1395/28
(c+2)^2 = 28
c = √28 - 2 ≈ 3.29

So, the desired month is later than 3, namely 4.

Answer 2

So basically round up this time, wow!