Question

The average cost per item, C, in dollars, of manufacturing a quantity q of cell phones is given by
C = \frac{a}{q} + b
where a and b are positive constants.

Find the rate of change of C as q increases. (Your answer may involve a and q.)

Answer 1

it's the derivative of C with respect to q.

Answer 2

Must have done something wrong the first time I tried it because it worked this time
The second part of this is
If production increases at a rate of 100 cell phones per week, how fast is the average cost changing? (Your answer may involve a and q.)

Answer 3

Which will be dC/dt somehow

Answer 4

Figured it out thanks