Question 178076
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:
{{{(y - y[1]) / (x - x[1]) = (y[2] - y[1]) / (x[2] - x[1])}}}
I'll say that
({{{x[1]}}},{{{y[1]}}}) = (6.7,100)
({{{x[2]}}},{{{y[2]}}}) = (10.2,80)
{{{(y - 100) / (x - 6.7) = (80 - 100) / (10.2 - 6.7)}}}
{{{(y - 100) / (x - 6.7) = (-20) /3.5}}}
Multiply both sides by {{{3.5*(x - 6.7)}}}
{{{3.5*(y - 100) = (-20)*(x - 6.7)}}}
{{{3.5y - 350 = -20x + 134}}}
{{{3.5y = -20x + 484}}}
{{{y = (-20/3.5)x + (484/3.5)}}}
If {{{y = 75}}} or,the price is $75
{{{75 = (-20/3.5)x + (484/3.5)}}}
{{{75*3.5 = (-20)x + 484}}}
{{{262.5 = (-20)x + 484}}}
{{{(-20)x = 262.5 - 484}}}
{{{(-20)x = -221.5}}}
{{{x = 11.075}}}
They can expect to sell 11,075,000 MP3 players