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    Word Problems: Direct Variation


    Direct variation type word problems encompass one variable, which is directly proportional to another variable:

    y = kx,

    where k is referred to as the constant of proportionality.

    Direct variation word problems often contain verbiage such as:
    • "varies directly as"
    • " varied directly as"
    • "directly proporation to"
    Direct variation word problems may be solved using the following steps:

    1) Recognizing the word problem consists of direct variation as exemplified by presence of verbiage listed above;

    2) Writing an equation containing known values for both variables resulting in an expression containing only the unknown representing the constant of proportionality;

    3) Solving the equation for the constant of proportionality;

    4) Using the calculated constant of proportionality to determine the value of one of the variables given the other.


    Example:

    The amount of money raised at a charity fundraiser is directly proportional to the number of attendees.  The amount of money raised for five attendees was $100.  How much money will  be raised for 60 attendees?

    Solution: