Use a Formula
Other than guessing, using formulas may be the second most frequently used problem-solving strategy. Formulas are also used in everyday life.
Matthew and Eric live 360 miles apart. They decide to meet for a weekend camping trip at a campsite that is halfway between their two hometowns. Matthew drives to the camp at an average speed of 60 miles per hour. Eric drives to the camp at an average speed of 45 miles per hour. How much longer will it take Eric to reach the camp than Matthew?
For this problem, students need to recognize to use the distance formula:
distance = rate x time
Then students need to adjust the formula so that they can solve for the time and substitute the values into the formula for both friends:
time = distance/rate
Finally, students need to go back to the first step of Find Out: "What is the question asking me to find?" and realize that they will have to subtract to find "How much longer it will take Eric to reach the camp?"
Answer: It will take Eric 1 hour more than Matthew to reach the camp. Did you realize that the distance was 180 miles. Why?: It will take Eric 1 hour more than Matthew to reach the camp. Did you realize that the distance was 180 miles. Why?
Make sure students are aware that the GED Mathematics Test provides a formulas page that can be used during the test. Review the formulas included on the page and how students can identify problems that require the use of the formulas.
You may wish to print a copy of the formulas page that is used on the GED Mathematics Test for your students. The formulas page is reprinted with permission of the GED Testing Service (c) 2001.
View and print the formulas page (pdf).
When you are finished, be sure to close the window by clicking on the X in the upper corner of the window of the formulas page.