Name _____________________________________________________________Day & Class ____________
I love Goldfish . . .
the cheesy kind.
With the school year underway, I am looking to get my favorite cheesy treat back in my
school lunch . . . Goldfish. I know they are not the best thing for me, but I don’t
think they are worst either. I feel that they are a sensible and tasty snack – and good
with any sandwich. While at the store I noticed three different Goldfish products. I
have listed the product, prices and amount of goldfish in ounces in the table below:
Product
Price
Total Ounces
Bag of Goldfish
$2
About 6 oz
Box of nine mini-packs of Goldfish, each 1 oz
$5
9 oz
Big box of Goldfish
$7
30 oz
1. I am planning on consistently buying Goldfish for my school lunch and snacks around
the house for a while. I don’t want my parents to think that my Goldfish snacks are too
costly, so I need to get a good deal. I also don’t know if I will be able to eat a big
box of Goldfish before they go bad, so I am a little worried that I could be wasting by
getting the big box. Create ratio tables for each Goldfish product to help me determine
which product to buy.
In case you don’t remember ratio tables, here is an example. Say Jelly Belly jelly beans
are $5 for 12 ounces. I can find the cost of various weights of Jelly Bellys by doing
some multiplying and dividing:
cost
ounces
$5
12
$10
24
$1
2.4
$15
36
$20
48
$25
60
$4.25
10
$.425
1
Make ratio tables comparing cost and ounces for each of the three Goldfish products. In
each ratio table find various cost/ounce relationships. Try to compare the three products
based on the same amount of ounces or the same price.
cost
ounces
cost
ounces
cost
ounces
Adapted from www.yummymath.com
Name _____________________________________________________________Day & Class ____________
2. Which product gives you the best deal on Goldfish?
your ratio tables to explain how you know.
Use details from your findings in
3. My siblings also love Goldfish. Mom says that she thinks
800 ounces a year in Goldfish. Assume that this is a correct
of ounces in that range that my family might go through. How
on Goldfish by always buying the big box versus the other two
and your reasoning below.
we go through about 700 to
estimate and pick a number
much will we save per year
products? Show your work
4. Under what condition might it make sense to buy either of the other two products that
have a higher cost per ounce?
Adapted from www.yummymath.com
Name _____________________________________________________________Day & Class ____________
5. We can visually represent the cost per ounce of the three products on a graph. You
will use the online graphing calculator at Desmos.com to graph the values from all three
Goldfish products’ ratio tables:
• Go back to your ratio tables from question #1
• Create a table for your first ratio table (click + and choose “Table”; then enter
your values)
• Repeat the process for the other two ratio tables
• Click the gear icon to edit the graphs of each ratio table. Click the colored
circles and select the circle that has small points connected by lines. This will
connect the points on the graphs of each of your ratio tables
• When you’re finished changing to the ‘connected points’ view, click Done
• Check to see if the connected points create a straight line. You may have to zoom
out by clicking the minus sign (on the right side of the graph) to see all of your
points. You may also need to slide the graph over (click and drag anywhere on the
graph) so that you’re just looking at the first quadrant of the graph.
• Did you have any points that don’t line up with the rest? Look back at your ratio
table to identify any mistakes. Make corrections in the table of values on
Desmos.com. Are the connecting lines straight now?
• If possible, print your graph. If you’ve created a Desmos.com account, you can save
your graph, print your graph, or share it (through email or through a URL). In
accordance with school policy, you MUST have parent permission to create an
account.
• If you didn’t create a Desmos account, you can print a screen shot or just print
the web page that shows your graph.
6. How do the graphs help you compare costs? How does the steepness of the graph’s more
expensive product compare to the steepness of the graphs of the less expensive products?
7. Sam’s Club may sell a giant box of Goldfish at an even cheaper cost per ounce then
the big box of Goldfish. Determine a box size in ounces and a cost that has a lower
price per ounce then the big box of Goldfish. Give the total ounces of Goldfish in the
box, the cost of the box, the price per ounce of the box, and describe how the cost per
ounce graph of this product would look compared to the other three graphs.
8. What are some different methods for determining what product is the best deal? For
example, what methods could you use to determine which is a better value, a 2-liter (2000
ml) bottle of Coke for $1.50 or a 355 ml of Coke for $0.70?
Adapted from www.yummymath.com