Cost of manufacturing skis

Question

C(s)=.01s³-s²+90s

a) find the cost of manufacturing 80 pairs of skis I. A month.

b) find the average cost per pair of manufacturing 80 pairs of skis in a month.

Answer 1

a) C(80) ... substitute 80 for s in the expression.

b) is the answer to a divided by 80, i.e. the average cost is C(s)/s

you should be able to do the calculations on your calculator!

To find the minimum average cost, divide C(s) by s and then set the derivative equal to 0

i.e C(s)/s= .01s²-s+90 and dC/ds=.02S-1 => minimum s=50