a Note that the best score is the point where the sum of the time and the strokes is the lowest.
B
b Discuss the association given the points around t=55.
C
c Do you think the correlation between time and strokes is positive or negative given the remaining points in the diagram?
D
d Use the gridlines to find two points through which the line passes.
E
e Note that Diego wants to minimize the sum of his time and strokes.
A
aScatterplot:
Best score: 122
B
b See solution.
C
cLine of best fit:
D
d m=2/3
E
e He should. See solution.
Practice makes perfect
a The number of strokes s depends on the time it takes to complete the course, t. Therefore, the number of strokes is the dependent variable and time is the independent variable. We will also circle the best total score, which is the lowest sum of time and strokes.
The best score is 45+77=122.
b Given what we see from the diagram, there is no clear association between time and the number of strokes. However, if we have to choose between a positive correlation and a negative, the observations clustered around t=55 shows a positive correlation.
c The only point that diverts from the other points in terms of time is (92,90). By crossing out that point, it becomes more clear that the association between time and strokes is a positive correlation.
d To estimate the slope of our line we need to find two points through which the line passes. Let's mark two such points on the line of best fit.
By substituting these point in the Slope Formula, we can determine the slope of the line.
e Since there is a positive correlation between time and strokes, and we want to minimize the sum of time and strokes. Diego should definitely train to reduce his time, as this also seems to minimize his number of strokes.
