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Federal Way Public Schools  
Communicates Understanding
Lesson 28
Organize, Represent, and Express
  Objectives/Vocab/Tips > Example: 1 | 2 | 3 > Practice: 1 | 2 | 3 > Reflection

Example 1:

Tracy and Vanessa are buying rocks for each of their fish tanks. The pet store uses different tags and a chart to show the prices of the rocks. For example, if a rock is in the basket with a triangle tab, then the price is 3 rocks for $1.00. Also, if a tag has a star on it, then the rocks in the basket are on sale for half-price.

Basket Tags
Price of Rocks
Basket Tags
Price of Rocks
3 for $1.00
2 for $1.50
2 for $1.00
3 for $2.00

Tracy bought 3 rocks from the basket with a hexagon and star and 6 rocks from the basket with a square.

Vanessa bought 4 rocks from the basket with a circle and 3 rocks from the basket with a triangle.

Who spent more money on rocks?

  1. Tracy
  2. Vanessa
  3. They spent the same amount.

Show how you got your answer using words, numbers, or pictures.

Let's begin solving this problem by using the six step problem solving process.

Step 1: Make sure that you understand the problem. An excellent way to to be sure you understand the problem is to restate the problem in your own words, as if you were explaining the problem to someone else.

In this problem there are two girls buying rocks for their fish tanks. Using the given chart and information about the cost of the different rocks, you need to find which girl spent more money on the rocks.

Step 2: To analyze the data given in the problem, you want to organize the facts and numbers you are given in this problem.

  • Tracy bought 3 rocks with the hexagon and a star and 6 rocks with a square.
  • Vanessa bought 4 rocks with the circle and 3 rocks with a triangle.

Step 3: To solve this problem you could make a simple chart or table to show how much each girl spent on the rocks. Using the different operations within the table you will arrive at the correct answer.

Step 4: Make an estimate or a guess as to who you think might have spent the most on rocks by looking at the data and not figuring the problem out.

Since Tracy has rocks that have a star on it, this means that the rocks are on sale, meaning she could have spent less since they are half price. Our estimate, Vanessa paid more for the rocks.

Step 5: Solve the problem using a table to see the answer.

Rocks
Tracy
Price Adjustment
3 rocks hexagon and star $2 for 3 rocks, star makes half price, so $1 for 3 rocks
6 rocks square $1 for 2 rocks, 3 sets of rocks, $3
  TOTAL $4

Rocks
Vanessa
Price Adjustment
4 rocks circle $1.50 for 2, 2 sets so, $3
3 rocks triangle $1.00 for 3, 1 set so, $1
  TOTAL $4

Step 6: Looking at our solutions, you find that both girls spent the same amount on rocks for their fish tanks. As you look at your choices you find that choice C gives you the option you are looking for. Therefore the first part or answer to the problem is C, both girls spent the same amount of money on the rocks.

To finish this problem, an explanation of your solution is required. Remember, be specific, be clear, and be complete in your explanation.

Your explanation can include the tables you made to solve the problem, but be sure to include an explanation of what you did in making your tables and why. You can even include your 6 steps used to solve the problem. To receive the two points for this problem, make sure that you answer the question for 1 point and then for the other point have a complete explanation.

Your explanation may look like this:

In this problem I had to find who spent the most money on rocks for their fish tank. To find out what Tracy spent on the rocks I know she bought 3 rocks with the hexagon tag, meaning the cost of those three rocks was $2, but since they also have a star on the tag, they are half price. Therefore, I know that those three rocks really cost $1. She also bought 6 rocks with a square tag. That means that for every 2 of those rocks it cost $1. Since she bought 3 sets of those to make 6 total, she spent $3 on those rocks for a total of $1 + $3 for a total of $4.

Vanessa bought 4 rocks with a circle tag which is 2 for $1.50. So 4 of these rocks would be two times $1.50 for a total of $3. Next she bought 3 rocks with the triangle tag which are 3 for $1. Add the two sets of rocks together and you get $3 + $1 which is also $4, just like Tracy.

This shows that both girls spent the same amount of money on the rocks, $4.

 

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