CPM Homework Help : GB8I Problem 9-39

A gallon of milk that cost $ $3.89$ a year ago now costs $ $4.05$ .

Hint:

Remember the independent variable ( $x$ ) represents years, while the dependent variable ( $y$ ) represents price.

More Help:

There are two points in this problem.
Point $1$ : $(-1, 3.89)$ one year ago cost $ $3.89$
Point $2$ : $(0, 4.05)$ now costs $ $4.05$ .

If the cost is increasing linearly, what is the growth rate? If the cost kept increasing in the same way, what will the milk cost $5$ years from now?

Hint (a):

Read the Math Notes box in Lesson 2.3.2 on finding equations of lines with 2 points.

More Help (a):

Remember that slope is $\frac{ \Delta y} { \Delta x}$

Answer (a):

Growth rate is $ $0.16$ per year. The price in $5$ years will be $ $4.85$ .

If the cost is increasing exponentially, what is the growth rate? What will the milk cost in $5$ years?

Hint (b):

Review problem 8-121 for a method of solving this problem.

More Help (b):

Remember there should be $2$ equations (system of equations) and use the Equal Values Method.

Answer (b):

The multiplier is $1.04$ ( $4$ %). The price in $5$ years will be $ $4.93$ .