∴ cardiac cycle T A = 1 sec
That is, it takes 1 s to move the ECG pattern by 25 mm
The moving speed of ECG drawing is v = 25mm/s.
(2)∵ It takes 20/25 s = 0.8s to move the drawing by 20/25s.
That is, b's cardiac cycle TB = 0.8 s.
∴ B 1 min, the heart rate is 60 s/0.8 s=75.