1. 2-9 Weighted Averages Mixture Problems Percent Mixture Problem
Speed of One Vehicle
Speed of Two Vehicles

2. A Quick Review 6r + t = r-1 Solve for r. 4c – d = 4a – 2c Solve for c
7𝑔+ℎ 𝑏 = -2 solve for h
Use the formula A= (a+ b ) to find the height of the trapezoid if a= 8 cm and
b = 17 cm.

3. A Quick Review
On a map, the distance between two cities measures inches. The scale of the map is ½ inch = 75 miles. What is the actual distance between the two cities?
EQ: Why is it important to be able to express mathematical expressions in different ways.
Activities for today:
Warm-up
Questions on homework
Review
Review vocabulary words from 2-8
Notes from 2-9
Classwork/Homework
You will be able to…
Solve mixture problems
Solve uniform motion problems

4. Weighted Averages New vocabulary Weighted average Mixture problem
Uniform motion problem
Rate problem
Madisha feeds her cat gourmet cat food that costs $1.75 She combines it with cheaper food that costs $0.50 per pound.
How many pounds of cheaper food should Mandisha buy to go with 5 pounds of gourmet food, if she wants the average price to be $1.00 per pound?
Units (lb)
Price per Unit
Total Price
Gourmet cat food
Cheap cat food
Mixed cat food

5. More examples
A car’s radiator should contain a solution of 50% antifreeze. Bae has 2 gallons of a 35% antifreeze. How many gallons of 100% antifreeze should Bae add to his solution to produce a solution of 50%?
Let g = the number of gallons of 100% antifreeze to be added. Fill in the table.
Amt of Solution (gal)
Amt of Antifreeze
35% solution
100% solution
50% solution

6. Real World Examples
A railroad switching operator has discovered that two trains are heading toward each other on the same track. Currently, the trains are 53 miles apart. One train is traveling at 75 miles per hour and the other 40 miles per hour. The faster train will require 5 miles to stop safely, and the slower train will require 3 miles to stop safely. About how many minutes does the operator have to warn the train engineers to stop their trains? r t
d=rt
Fast Train
Other train

7. Real World Examples
Cheryl bought 3 ounces of glass beads that cost $1.79 an ounce. The seed beads cost $.99 an ounce. How many ounces of seed beads can she buy if she only wants the beads to be $1.29 an ounce for her craft project?
Units (lb)
Price per Unit
Total Price
Glass
beads
Seed
Project beads

8. Real World Examples
A recipe calls for mixed nuts with 50% peanuts pound of 15% peanuts has already been used. How many pounds of 75% peanuts needs to be added to obtain the required 50% mix?

9. Real world examples
Two students left the school on their bicycles at the same time, one heading north and the other heading south. The student heading north travels 15 miles per hour, and the one heading south travels at 17 miles per hour. After about how many minutes will they be 7.5 miles apart?

10. Any additional questions