Question

Matthew has recorded the amount he's saved every three months. Months Savings 3 $1,800 6 $3,600 9 $5,400 Christopher saves $550 every month. Assume that Matthew and Christopher both save money at constant rates. Whose unit rate is higher, and by how much?

Answer 1

The correct answer is:

Matthew's rate is higher by $50 per month.

Explanation:

We know that Christopher's rate is $550 per month.

To find Matthew's rate, we will treat the data we have as ordered pairs:
(3, 1800)
(6, 3600)
(9, 5400)

We find the slope of the line between these points.  The formula for slope is:

$m=\frac{y_2-y_1}{x_2-x_1}$

Using the first two points, we have:
$m=\frac{3600-1800}{6-3}=\frac{1800}{3}=600$

To verify Matthew saves the same amount each month, we will find the slope between the second two points and make sure they're the same:

$m=\frac{5400-3600}{9-6}=\frac{1800}{3}=600$

Matthew's rate is $600 per month.
This is higher than Christopher's by 600-550=$50 per month.

Answer 2

Answer:

The answer is Matthew's savings per month is higher than Christopher's savings per month by $50 per month.

Step-by-step explanation: