Which is more economical?

Question

At the grocery store, Fred finds that the 10oz jar of pasta sauce costs $1.50, 24oz jar of pasta sauce costs $2.50 and the super-size 64oz jar costs $6.00. If Fred has a coupon for 50 cents off, which jar is more economical (on a per ounce basis)

Answer 1

You may notice that item prices in stores include a “unit price” so that this type of comparison is much easier.

So, what are the “unit prices?”

      a.   $1.50 per 10 oz

             $1.50/(10 oz)

             $0.15/oz  (or 15¢/oz)

 

      b.  $2.50 per 24 oz

            $0.104/oz   (or 10.4¢/oz)

 

      c. $6.00 per 64 oz

             $0.94/oz   (or 9.4¢/oz)

 

With the use of the 50 cents off coupon, the unit prices are:

 

     a.   ($1.50 – $0.50) per 10 oz

            $0.10/oz    (or 10¢/oz)

 

     b.  ($2.50 – $0.50) per 24 oz

           $0.083/oz   (or 8.3¢/oz)

 

     c.  ($6.00 - $0.50) per 64 oz

           $0.0859/oz  (or 8.59¢/oz)

 

Using the coupon, the 24-oz jar is more economical.