To calculate the average number of beats per second, you need to divide the total number of heartbeats by the total time in seconds.
If the graph or data gives you a total number of heartbeats (let's call it "Y") and a total time in seconds (let's call it "X"), then the calculation would be:
Average beats per second = Total Heartbeats (Y) รท Total Time (X)
Without the specific values from the graph, I can't provide the exact answer. However, if I had those numbers, I could determine the average beats per second for you. Please refer to the values given in the image and calculate accordingly.