Not sure how to do the last bit, help please.
Note: The cover is sometimes referred as a lid for some reason.
You didn't show the right equation for part (c)... =/
Area of two end sections =
Area of body of cover = [/tex]
Cost of end sections =
Cost of body =
Total cost =
Now,
Hence, cost =
4. I hope that you know some calculus... you'll have to find then solve for r.