To find the number of errors if the students typed zero words per minute, we substitute x=0 into the regression line:
y=3.473(0)-155.317
y=-155.317
Therefore, if the students typed zero words per minute, the regression line predicts they would make approximately -155 errors. However, since the number of errors cannot be negative, this value is not meaningful in this context.
For an increase of one word per minute typing speed, the regression line predicts an increase of 3.473 errors.
If a student types at 50 words per minute:
y=3.473(50)-155.317
y=173.65
The regression line predicts that the student would make approximately 173.65 errors.
If a student types at 70 words per minute:
y=3.473(70)-155.317
y=240.413
The regression line predicts that the student would make approximately 240.41 errors.
Based on the data and the regression line, it does support Mr. Moore's claim that the slower a student types, the fewer errors will be made. As typing speed increases, the regression line predicts that the number of errors also increases.