Lesson 3'9 Weighted Averages, pg' 171

1
Lesson 3.9- Weighted Averages, pg. 171

• Goals To solve mixture problems.
• To solve uniform motion problems.

2
Vocabulary

• Weighted average the sum of the product of the
  number of units and the value of units and the
  value per unit divided by the sum of the number
  of units.
• Mixture problems problems in which two or more
  parts are combined into a whole.

3
Ex. 1 Pets

• Jeri likes to feed her cat gourmet cat food that
  costs 1.75 per pound. However, food at that
  price is too expensive so she combines it with
  cheaper cat food that costs 0.50 per pound. How
  many pounds of cheaper food should Jeri buy to go
  with 5 pounds of gourmet food, if she wants the
  average price to be 1.00 per pound?

4
Auto Maintenance

• To provide protection against freezing, a cars
  radiator should contain a solution of 50
  antifreeze. Darryl has 2 gallons of a 35
  antifreeze solution. How many gallons of 100
  antifreeze solution should Darryl add to his
  solution to produce a solution of 50 antifreeze?

5
FOOD

• How many quarts of pure orange juice should
  Michael add to a 10 orange drink to create 6
  quarts of a 40 orange juice mixture? Let p
  represent the number of quarts of pure orange
  juice he should add to the orange drink.

6
Business

• Cookies Inc. sells peanut butter cookies for
  6.50 per dozen and chocolate chip cookies for
  9.00 per dozen. Yesterday, they sold 85 dozen
  more peanut butter cookies than chocolate chip
  cookies. The total sales for both types of
  cookies were 4055.50. Let p represent the
  number of dozens of peanut butter cookies sold.

7
METALS

• In 2000, the international price of gold was 270
  per ounce, and the international price of silver
  was 5 per ounce. Suppose gold and silver were
  mixed to obtain 15 ounces of an alloy worth 164
  per ounce. Let g represent the amount of gold
  used in the alloy.