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1.1 Order of Operations & Formulas

1.1 Order of Operations & Formulas
  • Math Help

    When you work with rates, use the units given to help solve the problem. For instance, if the problem asks for an answer in miles per hour, then your solution should include a quantity in miles divided by a quantity in hours.

    Similarly, if the problem asks for an answer in calories and you have a rate in calories per hour, your solution should include multiplying by hours to end up with just calories. See how this works in Example 5.


    This kind of approach to problem solving is called unit analysis and is an important tool used in many mathematical applications.

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  • Checkpoint Solution

    The total number of calories in your lunch is

    590 + 210 + 510 = 1310 calories for lunch

    At 155 pounds, running 10 miles per hour, you burn 1126 calories. At this rate you have to run

    1310cal x 1hr divided by 1126cal = approximately 1.16 hours

    to burn the calories you eat. This is about 70 minutes.

    How Do I Write a Rate?

    In the Math Help, you write the rate as 126 Cal divided by 1 hr

    In the Checkpoint Solution, you write it as

    Question:    How do I know which one to use?

    Answer:    This is a good question. The answer depends on the context of the problem.

    1. You know the units that are given.
    2. You know the units you need for the answer.
    3. Use unit analysis. That is, use the version of the rate that will convert the given units into the desired units.
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    Ron Larson (author)1 decade ago |
    There is some fascinating mathematics associated with fitness. Check it out in Section 10.1.