1. Volume (cm3) Surface Area (cm2)
6.4 Economy of Design
Volume (cm3) Surface Area (cm2)
Container #
Container #
Container #
The above are potential containers to be used by a company for a new product.
Which one do you think the boss might like to use? Why?
What other factors might influence the decision?
A # is often used to show how the volume compares to the surface area.
It is called the ECONOMY RATE – a rate (a # that compares 2 quantities) that compares the volume of a container to its surface area. E.R. = volume
surface area

2. 6.4 Economy of Design The higher the economy rate ……
the more economical
the larger the volume in relation to the surface area
The lower the economy rate ……
the less economical
the smaller the volume in relation to the surface area
Determine the economy rate for the containers above.
#1 E.R. = V = = 1.33
S.A
#2 E.R. = V = = 4
S.A
#3 E.R. = V = = 2
S.A
Therefore #2 is the most economical, its volume is 4 times its surface area.