Study Guide:
Weighted Averages

You can use charts to solve mixture problems.

Example 1: Alice Gleason invested a portion of $32,000 at 9% interest and the balance at 11% interest, How much did she invest at each rate if her total income from both inveestments was $3200?

Ms. Gleason invested $16000 at 9% and 16000 at 11%.

 

 

When an object moves without changing its speed, it is said to be in uniform motion. The formula d = rt is used to solve uniform motion problems.

Example 2: Bill Gutierrez left home driving at a speed of 54 miles per hour. How many hours did it take him to reach his destination 243 miles away?

It will take Bill 4½ hours to drive 243 miles.

 

Let's Practice: Solve each of the following problems.

1. How many grams of sugar must be added to 60 grams of a 32% solution to obtain a 50% solution?

 

 

21.6 grams

3. The Quick Mart has two kinds of nuts. Pecans sell for $1.55 per pound and walnuts sell for $1.95 per pound. How many pounds of walnuts must be added to 15 pounds of pecans to make a mixture that sells for $1.75 per pound?

 

 

15 pounds

2. Mr. Anders and Ms. Rich each drove home from a business meeting. Mr. Answers traveled east at 100 kilometers per hour and Ms. Rich traveled west at 80 kilometers per hous. In how many hours were they 100 kilmeters apart?

 

 

5 5/9 hours

4. Justin left home at 8:00 AM, riding his bike at 6 miles per hour. His brother Joshua left 2 hours later, riding his bike at 8 miles per hour. At what time will Joshua catch up to Justin if Joshua is delayed 15 minutes by a freight train?

 

 

5 PM