SOLUTION: 4. Suppose you have a cookie stand, and when you charge $3 per cookie box you sell 200 boxes. But when you raise your price to $4 you only sell 120 boxes. a. Write an equatio

Question 492864: 4. Suppose you have a cookie stand, and when you charge $3 per cookie box you sell 200 boxes. But when you raise your price to $4 you only sell 120 boxes.
a. Write an equation for the number of boxes you sell as a function of the price you charge.
b. Denote "B" for number of boxes, and "P" for the price you charge.
c. Assume the function is linear..
Found 2 solutions by josmiceli, stanbon:
Answer by josmiceli(19441) (Show Source): You can put this solution on YOUR website!
I will plot boxes on the x-axis and cost/box on the y-axis
Us the point-slope formula, which, in general is:

In this case, and
The given points are:
(3,200) and (4,120)

Multiply both sides by

check:
Does it include the given points?
(3,200)

(4,120)

OK
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
Suppose you have a cookie stand, and when you charge $3 per cookie box you sell 200 boxes. But when you raise your price to $4 you only sell 120 boxes.
----
You have two points: (3,200) and (4,120)
----
a. Write an equation for the number of boxes you sell as a function of the price you charge.
slope = (200-120)/(3-4) = -80
------
Form: # of boxes = mp + b
Solve for 200 = -80*3 + b
b = 440
------
Equation:
# of boxes = -80(charge) + 440
===================================================

b. Denote "B" for number of boxes, and "P" for the price you charge.
-------
c. Assume the function is linear..
B = -80*P + 440
=====================
Cheers,
Stan H.
==============

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