SOLUTION: A consumer electronics company sells 6.7 million MP3 players per month at a price of $100 apiece; when the price is lowered to $80, the company sells 10.2 million players per month

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Question 178076: A consumer electronics company sells 6.7 million MP3 players per month at a price of $100 apiece; when the price is lowered to $80, the company sells 10.2 million players per month. How many MP3 players can the company expect to sell per month at a price of $75?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
This is a linear relation, and you're given 2 points.
With 2 points you can plot the entire line. The points are:
(6.7,100) and
(10.2,80) where each unit on the x-axis is times 1 million
and the y-axis is dollars
The formula is:

I'll say that
(x%5B1%5D,y%5B1%5D) = (6.7,100)
(x%5B2%5D,y%5B2%5D) = (10.2,80)
%28y+-+100%29+%2F+%28x+-+6.7%29+=+%2880+-+100%29+%2F+%2810.2+-+6.7%29
%28y+-+100%29+%2F+%28x+-+6.7%29+=+%28-20%29+%2F3.5
Multiply both sides by 3.5%2A%28x+-+6.7%29
3.5%2A%28y+-+100%29+=+%28-20%29%2A%28x+-+6.7%29
3.5y+-+350+=+-20x+%2B+134
3.5y+=+-20x+%2B+484
y+=+%28-20%2F3.5%29x+%2B+%28484%2F3.5%29
If y+=+75 or,the price is $75
75+=+%28-20%2F3.5%29x+%2B+%28484%2F3.5%29
75%2A3.5+=+%28-20%29x+%2B+484
262.5+=+%28-20%29x+%2B+484
%28-20%29x+=+262.5+-+484
%28-20%29x+=+-221.5
x+=+11.075
They can expect to sell 11,075,000 MP3 players