Average Velocity in Scientific Notation

A physicist is conducting an experiment and records the following measurements of a particle's velocity over time:

1. $3.6 \times 10^4$ m/s
2. $7.2 \times 10^3$ m/s
3. $5.5 \times 10^5$ m/s
4. $2.3 \times 10^2$ m/s
5. $8.1 \times 10^6$ m/s

To analyze the particle's motion, he needs to find the average velocity of these measurements in scientific notation. What is the average velocity expressed in scientific notation?