Alejandro is selling HDMI cables on eBay, and is trying to determine the best price to sell at. For the last 10 weeks,

Question

 He plotted the results, and drew a line he feels fits the data well.

33.253.53.7544.254.54.75550100150Price ($)Quantity Sold

a) The line of best fit passes through the points (3.50, 130) and (4.75, 120). Find an equation for the line. 

Use variables: p for price in dollars, and Q for quantity of cables sold.



Answer 1

the slope is M = (130-120)/(3.50-4.75)

= 10/-1.25

= -8

Every time the price increases by $1, there are 8 fewer cables sold

Every time the price DECREASE by $1, there are 8 MORE cables sold...

B = y - mx = 130 - (-8)(3.50)

= 130 + 28

= 158

y = f(x) = -8x + 158

Q = f(p) = -8p + 158 is the demand function

if you can clarify the other data points, we can run them through

the regression calculator