Question

Each month, Stacey places a portion of her earnings in a retirement account. Her savings are invested in two companies. For every $9 invested in company A, $2 is invested in company B. Stacey quizzes her children, Krista and Kevin, about how much money she will invest in company A if she invests $24 in company B. Krista and Kevin used two different methods to arrive at the answer to Stacey’s problem. Let’s see who found the correct answer and how. You’ll answer some questions along the way.

Answer 1

y = kx

Let y be the independent variable, $9
Let x be the dependent variable, $2
Let k be the (constant) multiplier of x to get the product y.

First given: (y = 9 and x = 2)
9 = (k) (2)
9 ÷ 2 = k
4.5 = k

Second given: (x = 24)
Change x, while k remains constant
y = (4.5) (24)
y = 108

Stacey invested $108 dollars in company A.

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