Bulk candy $4.00 a pound and 1 pound fills a box 5 inches by 3 inches by 2in

Question

If bulk candy cost $4.00 a pound and 1 pound fills a box 5 inches by 3 inches by 2 inches, how much will it cost to fill a box 3 inches by 4 inches by 5 inches?

Answer 1

We can set a proportion.  Since the box has 3 dimensions, we can multiply them to get the volume.

 

The $4 a pound box has a volume of 30 in³.

 

We want to find the cost a pound that has a volume of 60 in³.

 

 

Set the proportion.

 

Ratio of cost = ratio of volume

 

4 / x = 30 / 60

 

 

x = the cost a pound that has the volume of 60 in³.

 

 

Cross-multiply.

 

30x = 240

   x = 8

 

It costs $8 a pound to fill the box 3 inches by 4 inches by 5 inches.