Answer
$75$ pulse beats per minute
Work Step by Step
To find the number of pulse beats in 1 minute, we first need to find the period. From the graph, it is obvious that the period is 0.8 seconds.
Using this period, we can find the frequency (the number of pulse beats in one second):
frequency$=\frac{1}{0.8}=1.25$ pulse beats per second
Since we now know the number of pulse beats per second, we find the number of pulse beats per minute by multiplying the answer by 60;
$60\times1.25=75$ pulse beats per minute