AP Statistics Quiz 3.3
Name:
In a laboratory experiment of two-dimensional diffusion, a small amount of detergent was dropped into a tank
of still water, and the area of water (in square centimeters) covered by a thin film of detergent at various times
(in seconds) was recorded. Computer output and a residual plot for the least-squares regression line are given
below.
Predictor Coef SE Coef
Constant -4.133
T
P
0.107
2.280 -1.81
3.0333 0.3675 8.25 0.000
S 3.33791 R-Sq- 89.58 R-Sq (adj) - 88.2%
Time
Residual (cm²)
-3-
-4
0
.
2
4
6
Time (seconds)
1. Give the equation of the least-squares regression line. Define any variables you use.
2. Use the model from part (a) to predict the area covered by detergent at 5.5 seconds.
8
10
3. Based on the residual plot, do you expect the prediction you made in part (b) to underestimate or
overestimate the area covered by detergent? Justify your answer.
4. Is the least-squares regression line an appropriate model for these data? Justify your answer.