Question

Zachary purchased a computer for 1100 on a payment plan. 4 months after he purchased the computer, his balance was $755. Five months after he purchased the computer, his balance was $640. What is an equation that models the balance b after m months. What does the slope signify is zacharys equation?

Answer 1

Model is

b = 115m + 65

The slope represents the amount of balance offset per month

Explanation:

Here, we want to model an equation.

The equation to model will be in the form;

y = mx + c

we have the following points to consider

The points are in the form;

(number of months, balance)

(m , b)

So the points we have are;

(4,755) and (5,640)

So the slope will be ;

(y2 -y1)/(x2-x1) = (755-640)/(5-4) = 115

So the equation will be;

b = am + c

where a is the slope and c is the y intercept

we already have the slope

so equation becomes;

b = 115m + c

let’s get the y-intercept

we can get the y-intercept by any of the points;

That would be; let’s use (5,640)

640 = 5(115) + c

640 = 575 + c

c = 640 -575

c = 65

So the equation of the model is;

b = 115m + 65

The slope represents the balance per month