Seraphina is driving two hours to visit her family. For the first hour, she traveled at a speed of 61 miles per hour. Then, in the second hour, she traveled at a speed of 72 miles per hour. What is the percentage increase of Seraphina's speed?

The percentage increase of Seraphina's speed=18.033%

Step-by-step explanation:

Step 1

Define the initial and final speeds as shown;

Initial speed=61 miles per hour

Final speeds=72 miles per hour

Step 1

Express the formula for calculating the percentage increase of Seraphina's speed as follows;

% increase={ (F-I) / I}*100

where;

F=final speed

I=initial speed

In our case;

F=72 miles per hour

I=61 miles per hour

replacing;

% increase={ (72-61) / 61}*100

% increase = (11/61) * 100=18.033%

The percentage increase of Seraphina's speed=18.033%