(5)率,比,變分,點計?

由於巧克力體積與成本成正比，所以必須知道巧克力體積才可以計算。

若r = 0.8及h = 1
圓錐形巧克力的體積,
V = 1/3 x 3.14 x r^2 x h
= 1/3 x 3.14 x 0.8^2 x 1
= 0.67 cm^3

即每0.67 cm^3巧克力的成本為$0.32
所以每1cm^3巧克力的成本為$0.32/0.67cm^3=$0.477 /cm^3

再計 r = 1及h=0.9時巧克力體積
V = 1/3 x 3.14 x r^2 x h
= 1/3 x 3.14 x 1^2 x 0.9
= 8.878 cm^3

所以成本為$0.477 /cm^3 x 8.878 cm^3 = $4.239

2007-02-22 14:16:57 補充：
打錯少少再計 r = 1及h=0.9時巧克力體積V = 1/3 x 3.14 x r^2 x h= 1/3 x 3.14 x 1^2 x 0.9= 0.942 cm^3所以成本為$0.477 /cm^3 x 0.942 cm^3 = $0.45

the first one is 0.67 volume is $ 0.32

one unit needed $0.4776

the second one is 0.9429 x 0.4776 = $ 0.45