Answer: The percentage increase of Seraphina's speed is 15.52 %
Explanation:
Total amount if time that Seraphina drove to visit her family is 2 hours.
For the first hour, she traveled at a speed of 58 miles per hour and in the second hour, she traveled at a speed of 67 miles per hour.
Increase in speed is the speed at which she travelled in the second hour - the speed at which she travelled in the first hour. It becomes
67-58 = 9 miles per hour
The percentage increase of Seraphina's speed is
(Increase in speed/ her speed in the first hour) × 100. This becomes
9/58 × 100
= 15.5172
15.52 %