Michigan State University - Diagnostic Exam

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3.20

  •   Sally is saving money for a new suit. She opens a savings account with an initial deposit of $30. The chart below shows how much money she has saved w weeks after opening the account.

    weeks

    		0 2 4 6 8 10

    amount saved ($)

    		30 70 110 150 190 230

    Which of the following expressions gives the amount of money w weeks after Sally opened the account?

    a) 40w + 30 b) 20w + 15 c) w + 40
       
    d) 30w + 40 e) 20w + 30

Solution:

The given data indicates that account value, V , is a linear function of w. Since the slope is 20 and the vertical intercept is 30, V = 20w + 30 .

Diagnostic:

See 2.7: Application (Reading Graphs) .

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July 15, 2008