- #1
alyplayford
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Homework Statement
The average cost per item, C, in dollars, of manufacturing a quantity q of cell phones is given by the following equation, where a and b are positive constants.
C = a/q + b
(a) Find the rate of change of C as q increases. Include units.
I already found this, it's: -a/q^2
***(b) If production increases at a rate of 130 cell phones per week, how fast is the average cost changing? Include units.
B is the one I need help with.
The Attempt at a Solution
So far for part "b", I've figured out that dq/dt is 130, so I differentiated C = a/q + b implicitlyand got dC/dt = -a/q^2 (dq/dt) + b. I plugged in 130 for dq/dt and got
dC/dt = -130a/q^2 + b
I have no idea where to go from here.
Any help would be greatly appreciated!