I need some help with this problem:

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.

I need to:

a) Find the average rate of change of

*S(t)* during the first year (rounded to 1 decimal place).

And:

b) During what month does

*S'(t)* equal the average rate of change during the first year?

I'm not too sure what to do for the first one. Some people have told me to find the derivative of the problem then plug 12 in for

*t*, but that's not right. I could probably find B after I find A.