Question

Timothy bought 10 cookies for $5.00. Let x represent the number of cookies purchased, and let y represent the total cost. Graph the line that represents the proportional relationship.

Answer 1

Y=.5x
5$/10cookies
each cookie is .50

Answer 2

Answer

The line that represents the proportional relationship is $y=0.5x$. Check the graph in the picture.

Explanation

We know that x represent the number of cookies purchased and y represent the total cost, so the unit cost of the cookies, which is the slop of the line, will be given by $m=\frac{y}{x}$

where

$m$ is the slope of the line

$y$ is the total cost

$x$ is the number of cookies

We know that Timothy bought 10 cookies for $5.00, so $x=10$ and $y=5$. Let's replace the values to find the slope of our line:

$m=\frac{y}{x}$

$m=\frac{5}{10}$

$m=0.5$

Now that we have the slope of our line, we can find the equation for the total cost of $x$ cookies:

$m=\frac{y}{x}$

$0.5=\frac{y}{x}$

$0.5x=y$

$y=0.5x$

Finally, to graph our line, we just need to plot tow points. We already know that Timothy bought 10 cookies for $5.00, so one point is (10, 5)

To find another point we can plug any number between 1 and 10 (the possible number of cookies Timothy can buy) for $x$ in our line equation. Let's say that the other point will be the total cost of 8 cookies, so $x=8$

$y=0.5x$

$y=0.5(8)$

$y=8$

Therefore, our second point is (8, 4)

Now we can join our point with our line as shown in the picture.