SOLUTION: Suppose you have a lemonade stand, and when you charge $1 per cup of lemonade you sell 50 cups. But when you raise your price to $2 you only sell 25 cups. Write an equation for t

Algebra ->  Functions -> SOLUTION: Suppose you have a lemonade stand, and when you charge $1 per cup of lemonade you sell 50 cups. But when you raise your price to $2 you only sell 25 cups. Write an equation for t      Log On


   



Question 173563: Suppose you have a lemonade stand, and when you charge $1 per cup of lemonade you sell 50 cups. But when you raise your price to $2 you only sell 25 cups. Write an equation for the number of cups you sell as a function of the price you charge. Denote "C" for number of cups, and "P" for the price you charge. Assume the function is linear.
My try at it:
1P = C50
2P = C25

Found 3 solutions by stanbon, Mathtut, josmiceli:
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
Suppose you have a lemonade stand, and when you charge $1 per cup of lemonade you sell 50 cups. But when you raise your price to $2 you only sell 25 cups. Write an equation for the number of cups you sell as a function of the price you charge. Denote "C" for number of cups, and "P" for the price you charge. Assume the function is linear.
---------
You have two points: (1,50) and (2,25)
slope = (25-50)/(2-1) = -25
-----------
Form: y = mx+b
intercept: 50 = -25*1 + b
b = 75
Equation:
C = -25p + 75
====================
Cheers,
Stan H.

Answer by Mathtut(3670) About Me  (Show Source):
You can put this solution on YOUR website!
we have 2 points we will label then (P,C) (1,50) and (2,25) so lets find the slope....change in C over change in P
:
25-50/2-1=-25 which is the slope of our equation...now lets the point slope formula ...I am going to use point (2,25)
:
C-25=-25(P-2)
:
C-25=-25P+50
:
highlight%28C=-25P%2B75%29
:
as you can see this can also be solved for P
:
divide all terms by -25
:
-C%2F25=P-3
:
P=-C%2F25%2B3
:

Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
The way to look at this is that you're graphing
price on the y-axis and cups on the x-axis.
Each point on the graph is (x,y) = (cups,price)
The problem gives you
(50,1) and
(25,2)
Since the problem says the relation is linear,
write the general equation for a straight line
y+=+mx+%2B+b where
m = slope
b = y-intercept
Now plug in the given points one at a time
(1) 1+=+m%2A50+%2B+b and
(2) 2+=+m%2A25+%2B+b
Solve for m and b
Subtract (1) from (2)
1+=+-25m
m+=+-%281%2F25%29
Plug this back into (2)
2+=+-%281%2F25%29%2A25+%2B+b
2+=+-1+%2B+b
b+=+3
So, the equation is
p+=+-%281%2F25%29%2Ac+%2B+3 answer
check the answer
Does it pass through the given points?
(50,1)
1+=+-%281%2F25%29%2A50+%2B+3
1+=+-2+%2B+3
1+=+1
(25,2)
2+=+-%281%2F25%29%2A25+%2B+3
2+=+-1+%2B+3
2+=+2
OK
If the price is 0 the equation says I'll sell
75 cups. I'd probably sell a lot more
When the price is $3, the equation says i'll sell
no cups because it's too expensive