a. The equation of the line of fit in slope-intercept form is: y = -328.275x + 3142.15
b. The trend, approximately 187.675 million CDs were sold in 2019.
a. Slope-intercept form is y = mx + b, so we need to solve for the slope (m) and y-intercept (b).
m = (y2 - y1) / (x2 - x1)
Substituting in our points, we get:
m = (1172.5 - 2485.6) / (6 - 2)
m = -328.275
Now that we know the slope, we can solve for the y-intercept by substituting one of our points back into the equation. This is called point-slope form:
y - y1 = m(x - x1)
Substituting in (2, 2485.6), we get:
y - 2485.6 = -328.275(x - 2)
y = -328.275x + 3142.15
Therefore, the equation of the line of fit in slope-intercept form is:
y = -328.275x + 3142.15
b. To find the number of CDs sold in 2019, we need to plug in 9 (2019 - 2010) for x in the equation:
y = -328.275(9) + 3142.15
y = 187.675
Therefore, according to the trend, approximately 187.675 million CDs were sold in 2019.
Question
The scattered plot shows the number of CDs in millions that were sold from 2011 to 2016.
a. Use the points (2, 2485.6) and (6, 1172.5) to write an equation of the line of fit in slope intercept form. Let x be the years since 2010.
b. If the trend continued, about how many CDs were sold in 2019?