SOLUTION: Suppose you have a lemonade stand, and when you charge 2 dollars per cup of lemonade you sell 120 cups. But when you raise your price to 3 dollars you only sell 60 cups. Write an

Algebra ->  Functions -> SOLUTION: Suppose you have a lemonade stand, and when you charge 2 dollars per cup of lemonade you sell 120 cups. But when you raise your price to 3 dollars you only sell 60 cups. Write an      Log On


   



Question 68852: Suppose you have a lemonade stand, and when you charge 2 dollars per cup of lemonade you sell 120 cups. But when you raise your price to 3 dollars you only sell 60 cups. Write an equation for the number of cups you sell as a function of the price you charge. Denote "C" for the number of cups, and "P" for the price you charge. Assume the function is linear.
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
The key to this one is that it is linear. You can then use a
formula for the slope of a straight line
As the price goes up, you sell less cups
$2/cup --- 120 cups
$3/cup --- 60 cups
Let c = number of cups sold
Let p = price per cup
c will take the place of y
and p will take the place of x in the formula

%28c+-+120%29+%2F+%28p+-+2%29+=+%2860+-+120%29+%2F+%283+-+2%29
%28c+-+120%29+%2F+%28p+-+2%29+=+%28-60%29+%2F+1
c+-+120+=+-60p+%2B+120
c+=+%28-60%29p+%2B+240 answer
check it
p = 3
c+=+%28-60%29%2A3+%2B+240
c+=+60
OK
p = 2
c+=+%28-60%29%2A2+%2B+240
c+=+120
Note that if you sell for $4/cup, you won't sell any cups