Monday . . . . . 2.5 miles
Tuesday . . . . . 4.6
Thursday . . . . 6.75
Saturday . . . . . 4.8
Total = 18.65 miles
Days per week = 4
Average miles per running day = 18.65/4 = 4.6625 miles
Rounded to the nearest 0.01 = 4.66 miles per running day
Because the second derivative of the function at the point is negative, the graph must be concave down at this point. Because the first derivative indicates that the function is also likely to be a maximum or minimum, the point must be a maximum.