What is the average rate in meters per second, at which these six dolphins swam during this observation
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Arithmetic mean works on each point of the graph:
[tex] \frac{\sum n}{n} [/tex] = [tex] \frac{40 + 30 + 60 + 50 + 90 + 80}{6} [/tex]
~ This yields 58.33 m/s.