Study Guide: Weighted Averages

These web-based activities were developed, during summer sessions from 1997 through 1999, by students at Mainland High School, located in Daytona Beach, FL. As part of Mainland's CCTT grant, the students were given permission by the book's publisher to convert the ancillary materials of the County's adopted Algebra 1 Textbook (Glencoe Algebra 1 - ISBN: 9780028253282) into html format.

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