Tuesday, August 14, 2012

Working with ratios

August 14, 2012 - Ratios

Class Opening -
Welcome! Please begin by meeting your group members from last class at your whiteboard. You should each have a solution to the Leaky Faucet problem. I want each of you to contribute to the solution. Please do the following:

  1. Listen to the solution provided by each person in the group. It is important to allow even those of us with the quietest voices time to explain ideas.
  2. If different solutions are provided, decide as a group how you will write up the solution.
  3. Be organized as you write up the solution.
  4. You will present your solution to the other group.

By the end of class, I should be able to:
  • write two equivalent ratios
  • identify key information in ratios word problems
  • solve word problems using ratios

Class Syllabus

Create a Table of Contents

Key Vocabulary
  • Ratio
  • Equivalent
Vocabulary Words of the Month
  • Contribute
  • Elaborate



Vocabulary - Please write your own meaning for the word “ratio”.

Working with Ratios:

1.This negative, when developed will produce a 4" by 6" photograph.
  What is the length of each negative, if the width is 24 millimeters?
What does the question want you to find?
What important information is given?
What ratios can you write for this problem?
Describe how you will solve the problem.



Problem Solution:                                                                



2. Hugh uses 13 grams of coffee powder to each liter of water.    He has a cup which holds 0.3 liters of water. How much coffee powder should he use?

Make a sketch of this problem that shows important information.



What does the question want you to find?
What ratios can you write for this problem?
Describe how you will solve the problem.



Problem Solution:




3. On average, I sleep about 7 hours 45 minutes each day. So, during one year, I sleep for  
                           7.45 x 365 = 2719.25 or about 2700 hours.

   This calculation is not correct. What is the correct answer?
What does the problem ask you to do?
What important information is given?
What ratios can you write for this problem?
What has been done incorrectly?



Problem Solution:   



4.John’s collection contains US, Indian and British stamps. If the ratio of US to Indian stamps is 5 to 2, and the ratio of Indian to British stamps is 5 to 1, what is the ratio of US to British stamps?

What does the question want you to find?
What important information is given?
What ratios can you write for this problem?
Describe how you will solve the problem.



Problem Solution:





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