Answer:
Step-by-step explanation:
The line that best fits is
[tex]y=-0.03x+3.45[/tex]
Where [tex]x[/tex] is days and [tex]y[/tex] is time in minutes. So, we have [tex]x=15[/tex], replacing this in the equation and solving for [tex]y[/tex], we have
[tex]y=-0.03(15)+3.45=-0.45+3.45=3[/tex]
Therefore, on the 15th day his best time for the day is 3 minutes.