A regression line has intercept = 2 and slope = 9.  What is the residual for the observation (x,y) = (8,76.1)?

To calculate the residual for the observation (x,y) = (8,76.1), you need to follow these steps:

1. First, calculate the predicted value (y') using the regression line equation y' = mx + b, where m is the slope, x is the x-value of the observation, and b is the y-intercept. In this case, m = 9, x = 8, and b = 2. So, y' = 9*8 + 2 = 74.

2. Then, calculate the residual, which is the difference between the observed value (y) and the predicted value (y'). In this case, y = 76.1 and y' = 74. So, the residual = y - y' = 76.1 - 74 = 2.1.

So, the residual for the observation (x,y) = (8,76.1) is 2.1.