161k views
6 votes
NEED ASAP!!!!!

The graph shows a school's profit for selling lunches
on pizza day. What is the cost for selling 100
lunches? You must show your work.

NEED ASAP!!!!! The graph shows a school's profit for selling lunches on pizza day-example-1
User Salami
by
7.0k points

1 Answer

3 votes

Answer:

The cost for selling 100 lunches is 150 dollars.

Explanation:

First, consider the equation: y = mx + b
y in this case is the profit in dollars (what' on the y axis) x in this case is the number of lunches sold (x- axis), m is the slope.

How do we calculate the slope of a graph? we take two points from the graph, let's say, (65,45) and (20,-90)

the formula for finding the slope is:


(rise)/(run) = (y2 - y1)/(x2-x1) \\\\

where (x1, y1) is coordinates of first point in the line

where (x2, y2) is coordinates of second point in the line


(45-(-90))/(65-20) = 3

m = 3

y = 3x + b

now we need to find b. We just insert one point of your choice from the grpah, let's choose (50,0) now plug them in out newfound equation (y = 3x + b)

0 = 3(50) + b

find b using algebra:

0 = 150 + b

b = -150

Yay! we found b, now we have the equation y = 3x - 150

(by the way I just noticed you can find b from the graph, the point that touches the y-axis is b)

now we are told to find the cost for selling 100, we need to plug in 100 instead of x in our equation.

y = 3(100) - 150 = 150

therefore the cost is 150 dollars.

hope this helps, tell me if you misunderstood something.

User Sapbucket
by
7.7k points

No related questions found

Welcome to QAmmunity.org, where you can ask questions and receive answers from other members of our community.