Rafael is analyzing data about the price of a certain stock in his finance class. he finds the linear regression line for the data to be f(x) = 0.76x + 42.39, where x is the number of days since rafael started observing the stock's price and f(x) is the price in dollars of the stock after x days of observation. if the point (15, 52.04) is in the original data set, what is the residual for when x = 15?

For this case, the first thing to do is to use the equation of the given line.
 We have then:
 f (x) = 0.76x + 42.39
 We substitute the value of x = 15:
 f (15) = 0.76 * (15) + 42.39
 f (15) = 53.79
 Then, subtracting with the original value we have:
 53.79-52.04 = 1.75
 
 the residual for when x = 15 is:
 1.75

D

Step-by-step explanation:

10*20=200

200 + 1020= 1220

Works for the first one

20*20=400

400+ 1020=1420

Works for the second one

30*20=600

600+1020=1620

Works for the third one, and all the others one so forth.

You take the number on the left (10, 20, 30, 40, 50, 60, 70) and times it by 20, replacing the x in the equation with the number on the left side of the table. Then you add the number from said equation to result of the multiplication from the first step.